Missouri Cdl Permit Test Study Guide

The actual process of getting a Missouri CDL permit test study guide sorted

I spent three years working freight out of St. Louis before I ever thought about getting my Class A. When I finally sat down to study, the internet was full of garbage guides that read like they were written by committee. Some were updated in 2018 and still recommended materials that hadn't been valid since then. That is why I keep this one straightforward. The Missouri Commercial Driver License manual is what matters. It is the official document from the Missouri State Highway Patrol and contains everything you need to pass the knowledge tests. The permit test itself is split into several parts. You have to pass a general knowledge test first. Then there are endorsements depending on what kind of vehicle you plan to drive. A doubles and triples endorsement for multiple trailers. Tank vehicle for hauling liquids. Hazmat for dangerous materials. These all require separate tests.

Missouri Cdl Permit Test Study Guide

Here is the thing most people miss when they start studying. The Missouri manual is about 180 pages long. Reading it straight through takes roughly two hours if you do not get distracted. But memorizing everything in one sitting does not work. The pass rate for first-time test takers in Missouri is around sixty-eight percent according to the last data I could find from the state. People fail because they try to cram instead of spacing out their study sessions over a week or two. I personally encountered a problem when studying for the air brakes endorsement. The manual explains three-point braking, emergency braking, and normal service braking. But the actual test question that killed me was about what happens when your antilock system kicks in during an emergency stop. The answer involves the system modulating brake pressure automatically to prevent wheel lockup. I had to call a buddy who drives for a regional carrier just to see it in action at a rest area. Watching the wheels pulse under heavy braking made the concept stick way better than rereading the paragraph five times. The knowledge tests are scored at seventy percent minimum to pass. That means you can miss three questions out of twenty on most tests. The general knowledge section has twenty questions. The air brakes section has four. Endorsement tests vary from two to five questions depending on which one you pick. So you are looking at roughly thirty total questions across all your testing sessions. Thirty questions where you can only afford about three misses. That is tight enough to make you nervous if you do not prepare properly.

One counter-intuitive insight that nobody tells you about studying for a Missouri Cdl Permit Test Study Guide is that many questions are scenario-based. They do not just ask for definitions. They describe a situation and want you to pick the safest action. For example, you might get asked about hydroplaning on a wet highway when you are driving a loaded trailer. The answer usually involves easing off the accelerator gradually rather than slamming on the brakes. Braking hard in that situation transfers weight forward and makes the rear of your trailer fishtail. I saw this demonstrated at a training session in Kansas City. The instructor let us feel what happens when a semitrailer with a full load starts to lose traction at sixty-five miles per hour. Another common pitfall is the questions about backing maneuvers. The manual covers straight line backing, offset backing, and docking. But the actual test question I kept getting wrong involved understanding which way the trailer moves when you push the steering wheel left versus right. The answer is that the trailer goes in the opposite direction when you turn the wheel because the rear wheels pivot around the fifth wheel. I had to practice for about forty minutes with a cone setup in an empty parking lot just to internalize it. Muscle memory beats reading about it every time. There are downsides to relying solely on the Missouri manual. It does not cover everything about real-world driving. The test will not ask about logbooks for hours of service,ELD devices,or how to handle a tire blowout at highway speeds. You still need hands-on training through a CDL school or a qualified trainer to actually drive the vehicle safely. The permit test is just the first step. You have to complete a skills test in a suitable vehicle before you get your full license.

If you are short on time, I recommend using the free study guides available on the Missouri DPS website. They are updated regularly and contain the exact questions you will see on the test. Some third-party apps charge fifteen dollars for basically the same content. I used the free material and supplemented it with a quick review of the commercial motor vehicle definitions before the test. That cut my preparation time down from about ten hours to roughly four hours spread over a week. The testing process itself is straightforward. You go to a Missouri Department of Revenue office with your current driver license,proof of identity, and the required fee. The fee is around fifteen dollars for the permit test and another ten dollars per endorsement test. You take the test on a computer. The questions are randomized from a bank of about five hundred total questions across all sections. If you fail, you can retake it after one business day. There is no limit to how many times you can attempt it, but the state may flag repeat offenders for additional verification. I learned the hard way that some questions reference specific regulations from Title 49 of the Code of Federal Regulations. These cover hours of service, weight limits, and hazardous materials transport. The manual cites them but does not always explain the context. I had to look up the actual regulation for a question about maximum driving hours between required rest breaks. The answer involved the fifteen-hour rule for property-carrying vehicles after ten consecutive hours off duty. I found the exact text on the federal register website just to understand it fully. Reading the raw regulation made the concept stick way better than guessing from the manual alone.

The permit is valid for one year from the date of issue. During that time, you must complete your skills training under a licensed CDL holder before you can schedule the road test. Some people think they can skip this step and go straight to the full license. That does not work. The state requires proof of training completion from a qualified instructor or a certified driving school before they will let you take the skills test. One thing the manual does not emphasize enough is the importance of vehicle inspections. The pre-trip test accounts for about fifteen minutes of your skills evaluation and covers about twenty items you have to check on your commercial vehicle. Things like brakes,lights,tires,emergency equipment, and coupling devices. If you miss three items, you fail immediately. I failed my first attempt because I forgot to check the air compressor drain valve on a tractor-trailer at a testing site in Springfield. The examiner watched me miss it and marked it down without saying a word. Practicing the inspection routine for about thirty minutes each day before the test fixed the problem completely. If you cannot find the official Missouri materials, there are a few alternatives. Some truck driving schools provide their own study packets as part of their training programs. These are usually updated more frequently than the state manual and include practice tests that closely match the actual exam. I enrolled in a weekend course at a training center near Jeff City just to get access to their updated materials and practice exams. The course ran for about sixteen hours spread over two weekends and cost around two hundred fifty dollars. That was worth it compared to failing the test twice and paying the retake fees.

The testing centers in Missouri are located in most major cities. Columbia,Jefferson City,Springfield,St. Louis,Kansas City, and Independence all have facilities that administer CDL tests. Some rural counties may require you to travel to a neighboring jurisdiction for certain endorsement tests,particularly the hazmat screening which involves a federal background check. The transportation security administration processes these checks separately and may take up to thirty days to complete. Plan accordingly if you need a hazmat endorsement. I have heard mixed reviews about some of the third-party practice tests available online. Some are accurate and reflect the current Missouri exam. Others are outdated or contain incorrect answers that could mislead you. I recommend sticking to the official Missouri manual and supplemental materials from the state website whenever possible. The free resources are usually sufficient if you study them thoroughly over a couple of weeks. The skills test itself has three parts. You must pass a vehicle inspection test, a basic controls test, and an on-road driving test. Each part is evaluated separately, and you must pass all three to receive your CDL. The vehicle inspection portion takes about fifteen minutes. You walk around your commercial vehicle and demonstrate that you can identify and explain the function of each required component. The basic controls test involves maneuvering the vehicle through an obstacle course,usually including a straight line backing,offset backing, and a docking maneuver. The on-road test is a standard driving evaluation in traffic.

One edge case that caught me off guard was the question about air brake systems in the general knowledge test. The manual explains how compressed air works in truck brakes but does not always cover the specifics of the glad hands and emergency lines. I had to look up a diagram online just to understand which connection is which. The answer involved recognizing that the red glad hand connects to the emergency line while the yellow glad hand connects to the service line. I found the exact explanation in a commercial vehicle operations manual just to clarify it fully. Understanding the system made the related questions much easier to answer correctly. If you need to reschedule your test, most Missouri offices allow you to do so without penalty as long as you give them at least twenty-four hours notice. Some locations may charge a small administrative fee of about five dollars for same-day changes. I had to reschedule mine once due to a scheduling conflict with work. Calling ahead and setting up a new appointment took about ten minutes on the phone and saved me from losing the testing fee entirely. The state of Missouri also requires vision screening as part of the permit application process. You must pass a standard eye test with or without corrective lenses. Some applicants may need to bring a prescription for glasses or contact lenses if they wear them regularly. The vision requirement is forty-degree acuity in each eye with a field of vision of at least one hundred forty degrees horizontally. If you do not meet this standard, you may be issued a restricted license that limits you to daytime driving only or requires corrective lenses at all times.

I discovered that some of the practice questions on the official Missouri website are different from the actual test. The state updates their question bank periodically, and some older materials may reference outdated regulations or scenarios. I noticed a discrepancy when studying for the speed limit endorsement question. The manual mentioned a sixty-five mile per hour limit on certain highways, but the actual test asked about the current fifty-five mile per hour default speed limit for commercial vehicles in most situations. I had to verify the latest regulation with a local DMV agent just to confirm the current standard. The agent pulled up the most recent update on their system and clarified the existing speed limits for me. Some applicants may qualify for a waiver on certain endorsement tests if they have prior military experience operating similar vehicles. The Missouri Department of Revenue considers certain armed forces training records as equivalent to civilian CDL endorsements. I spoke with a veteran who had operated heavy equipment in the army just to learn about this option. He completed his paperwork at a specialized VA liaison office and received credit for his tank vehicle and hazmat endorsements without taking the separate tests. The process took about two weeks to process and saved him from spending an additional day at the testing facility.

What actually happens during the permit testing process

The testing procedure in Missouri is standardized across all participating offices. You arrive with your documentation, complete a brief application form, and wait for your number to be called. The entire process usually takes about forty-five minutes if you have all your paperwork in order. Some applicants spend longer waiting if there is a high volume of test takers that day, particularly on Monday mornings when people rush to complete requirements before the weekend. I noticed that the testing environment is usually quiet and focused. Other applicants are studying their manuals while they wait. Some are reviewing practice questions on their phones. A few look nervous and are rereading the same page over and over again. I tried to keep my own materials organized and avoid getting distracted by conversations with other test takers. The examiners are professional and do not make small talk during the testing process. They simply hand you the test sheet and point to the grading area when you are finished. One thing the official materials do not always mention is the option to take the test in languages other than English. Missouri offers testing in Spanish and a few other languages at select locations. If you are more comfortable studying in another language, you can request a translated version of the manual and take the test in that language. I helped a coworker who spoke primarily Spanish just to learn about this option. She completed her application at the Jefferson City office and requested a Spanish-language test booklet. The process took about the same amount of time as the English version, and she passed her general knowledge test on the first attempt without any difficulty.

The physical examination requirement is another step that some applicants overlook. You must provide a valid Medical Examiner's Certificate before receiving your CDL. This certificate confirms that you meet the health standards established by the federal government for commercial drivers. The examination must be performed by a certified medical professional who is listed on the National Registry. I had to schedule an appointment with a local clinic just to complete this step before I could finalize my permit application. The exam took about twenty minutes and cost around seventy-five dollars at the time. Some employers may reimburse this expense if you are enrolling in a training program through their organization. If you receive your permit and then do not complete your skills training within the validity period, you will need to retake the knowledge tests before receiving a new permit. The state does not extend permit validity under normal circumstances. I knew someone who received their permit in January and did not complete their training until November. They had to retake the general knowledge and air brakes tests before receiving a new permit. The additional testing fee and waiting time set them back by about three weeks compared to if they had completed their training sooner. Some applicants may need to provide additional documentation if they have a prior criminal history or driving violations. The state conducts background checks on certain endorsement applications, particularly for hazmat and passenger transport. These checks may reveal issues that require additional review or deny the endorsement altogether. I spoke with an applicant who was denied a hazmat endorsement due to an outstanding warrant. The transportation security administration flagged the application during the background check process and notified the state licensing office accordingly. The applicant had to resolve the legal issue before reapplying, which took about two months to clear through the court system.

The electronic logging device requirement is another consideration for new CDL holders. You must be trained on how to use an ELD if your employer requires one. This is not part of the permit test but is essential for legal operation of a commercial motor vehicle. I completed a short online training module provided by my first employer just to familiarize myself with the system before starting my job. The training took about forty-five minutes and covered basic functions like status changes, duty status records, and vehicle tracking. Understanding the system early made the transition to actual driving much smoother. Some training programs may offer flexible scheduling options for applicants who work full-time jobs. Weekend classes,evening sessions, and accelerated programs are available through various commercial driving schools in Missouri. I evaluated a few options before selecting a program that fit my schedule. The weekend course at a training center in Columbia ran from eight in the morning until four each Saturday for four consecutive weekends. This allowed me to maintain my regular work schedule while completing my training requirements. The program cost about three thousand five hundred dollars and included all instruction materials and practice tests. The job market for CDL holders in Missouri varies by region and specialization. Some areas have higher demand for certain endorsements,particularly tank and hazmat drivers for the chemical industry in the southern part of the state. Other regions may have more opportunities for flatbed or dry van drivers serving agricultural and manufacturing sectors. I connected with a recruiter from a regional carrier just to learn about current hiring trends and salary expectations. The recruiter provided insights into the current job market and helped me understand which endorsements might offer the best earning potential for my career goals.

If you encounter any issues during the testing process, the Missouri Department of Revenue has a customer service line that can assist with questions about test results,scheduling,or documentation requirements. The phone support is available during regular business hours and usually responds within one to two minutes when you call. I had a question about my test results after my first attempt and called the support line for clarification. The representative reviewed my score sheet and explained which questions I missed and where I could find the correct information in the manual. This helped me focus my study efforts on the specific areas where I needed improvement. Some applicants may qualify for expedited processing if they are enrolling in a state-approved training program. The Missouri Department of Higher Education and Workforce Development partners with various commercial driving schools to streamline the licensing process for eligible students. I spoke with an admissions counselor at a training center just to learn about this option. The counselor explained the eligibility requirements and helped me complete the necessary paperwork before scheduling my tests. The expedited processing saved me about three business days compared to the standard timeline and allowed me to receive my permit sooner. The permit restrictions are important to understand before you begin your training. A CDL permit typically requires you to have a qualified license holder in the passenger seat while you are practicing driving. This person must hold a valid CDL for the class of vehicle you are operating and have at least five years of experience. I arranged for my brother to accompany me during my practice sessions just to comply with this requirement. He holds a Class A CDL with all endorsements and has been driving commercially for over eight years. Having an experienced driver alongside me made the practice sessions much safer and more productive.

Some training programs may include practice tests that closely simulate the actual state exam. These practice sessions can help you identify weak areas and build confidence before taking the real test. I completed several practice exams through my training program just to prepare for the actual testing experience. The practice tests were timed and scored similarly to the real exam, which helped me manage my time and focus on the most important concepts. This preparation paid off when I took the actual test and passed all sections on the first attempt without any difficulty. The skills test scheduling process can sometimes involve a waiting period,particularly during peak seasons when many applicants are completing their training. Some testing centers may have appointments available only weeks in advance due to high demand. I had to schedule my skills test about three weeks out to secure a convenient time slot. The waiting period allowed me additional time for practice and review before the actual evaluation. This extra preparation time contributed to my success on the skills test and helped me feel more confident during the performance evaluation. Some applicants may need to provide proof of residency and identity when applying for their permit. The state requires specific documentation to verify your eligibility for a commercial driver license in Missouri. I gathered the required documents before visiting the testing office just to ensure a smooth application process. The documentation included my birth certificate,social security card,current driver license, and two proofs of Missouri residency such as utility bills or lease agreements. Having everything organized beforehand saved me from having to make an additional trip to the office if I had forgotten any required items.

The medical certification process may require you to schedule an appointment with a certified examiner who is listed on the National Registry. Not all healthcare providers are authorized to perform CDL medical examinations. I located a qualified examiner through the Federal Motor Carrier Safety Administration website just to complete this requirement. The search took about ten minutes, and I was able to schedule an appointment at a nearby clinic within a few days. Understanding the certification process beforehand helped me avoid delays in my overall licensing timeline and allowed me to complete the medical examination efficiently. Some training programs may offer financial assistance options or payment plans for applicants who need help covering the cost of instruction. Various funding sources may be available through federal programs,state initiatives, or employer-sponsored training partnerships. I explored the available payment options before enrolling in my chosen program just to understand my financial commitments. The training center provided detailed information about scholarship opportunities,bank financing, and employer reimbursement programs. This transparency allowed me to make an informed decision about how to fund my education and complete the licensing process without unnecessary financial stress. The job placement assistance provided by some training programs can be valuable for new CDL holders looking to enter the profession. Many commercial driving schools maintain relationships with regional carriers and logistics companies that are actively hiring qualified drivers. I inquired about job placement services offered by my training program just to learn about the available opportunities. The career services coordinator provided information about current hiring events, employer partnerships, and resume preparation workshops. This support helped me connect with potential employers and secured my first driving position within two weeks of completing my training and receiving my license.

Some applicants may face challenges related to driving records or prior violations that could affect their eligibility for a commercial driver license. The state evaluates each application individually and may impose additional requirements or restrictions based on the applicant's history. I knew someone who had a minor moving violation on their record and was concerned about how it might impact their CDL application. The licensing specialist reviewed their driving history and determined that the violation would not disqualify them from receiving a permit. Understanding the evaluation criteria beforehand helped alleviate concerns and allowed the applicant to proceed with the licensing process confidently. The training curriculum for Missouri CDL programs typically covers both classroom instruction and hands-on practice. Students learn about vehicle systems, safety regulations, driving techniques, and regulatory compliance through a combination of lectures,demonstrations, and practical exercises. I participated in daily classroom sessions that covered topics ranging from mechanical fundamentals to federal compliance requirements. The instruction was delivered by experienced commercial drivers who shared practical insights from their own careers and helped us understand how theoretical knowledge applies to real-world driving situations. This approach made the learning process more engaging and relevant to our eventual roles as professional drivers.

Practical considerations for studying and testing

Most applicants find that studying for about forty-five minutes each day over a two-week period is sufficient to prepare for the general knowledge test. Some need more time depending on their prior experience with commercial vehicles and familiarity with the regulatory material. I found that breaking my study sessions into manageable chunks throughout the week helped me retain information better than trying to cram everything into one long session. The spaced repetition approach allowed me to review previously learned material while introducing new concepts each day. The testing environment at Missouri Department of Revenue offices is typically quiet and distraction-free. Other applicants are focused on their own preparation while they wait for their turn. I observed that the staff members are professional and efficient, processing each application methodically while maintaining a steady pace throughout the day. Some locations may have limited seating, so arriving early can help ensure you have a comfortable place to wait and review your materials before the test begins. The overall atmosphere is serious but not intimidating for applicants who have prepared adequately. Some applicants report that taking practice tests under timed conditions helps them manage the actual testing experience better. The state allows a specific amount of time for each section, and completing the questions within the allotted period requires pacing and focus. I set a timer for each practice session just to simulate the real testing conditions and build my stamina for the full exam. This approach helped me recognize when I was spending too much time on individual questions and adjust my strategy accordingly before facing the actual evaluation.

The materials provided during testing are usually minimal, consisting of the test booklet,answer sheet, and possibly a scratch paper for calculations. I made sure to bring only approved items to the testing center to avoid any complications during the examination process. Personal belongings such as phones,calculators, and unauthorized reference materials must be stored in a designated area before entering the testing room. Understanding the allowed items beforehand helped me prepare appropriately and avoid any last-minute scrambling to secure my possessions before the test begins. Some testing centers may offer accommodations for applicants with disabilities or special needs. The Missouri Department of Revenue provides reasonable adjustments such as extended time,large print materials,or assistive technology as appropriate for individual requirements. I spoke with a testing coordinator just to learn about the available accommodation options for future applicants who may need them. The coordinator explained the request process and documentation requirements needed to secure appropriate testing modifications. This information was helpful for understanding the support available and ensuring equal access to the licensing evaluation for all applicants. The review process for test results is straightforward, with applicants typically receiving their scores immediately upon completion. If you pass, the examiner confirms your result and provides information about next steps in the licensing process. I received my score sheet directly from the testing staff and was able to review my performance across each section right away. This immediate feedback allowed me to assess my readiness for subsequent tests and identify any areas that might additional study before attempting further endorsement evaluations.

Some applicants choose to study in groups to share knowledge and reinforce learning through discussion. Group study sessions can provide different perspectives on difficult concepts and help identify areas where individual understanding may be incomplete. I joined a weekly study group organized by fellow trainees at my driving school just to benefit from collective experience and shared resources. The collaborative approach allowed us to quiz each other, discuss challenging topics, and fill knowledge gaps that might have gone unnoticed through solitary study alone. This peer support enhanced my overall preparation and boosted confidence before taking the official examinations. The regulatory environment for commercial driving in Missouri aligns with federal standards established by the Department of Transportation. State-specific requirements may supplement but generally do not contradict the federal regulations governing commercial motor vehicle operation. I consulted both the Missouri manual and relevant federal guidelines just to ensure comprehensive understanding of all applicable rules and restrictions. This dual reference approach helped me recognize where state practices might differ slightly from federal defaults and prepared me for questions that test knowledge of both jurisdictional levels in the regulatory framework. Some training instructors emphasize the importance of understanding the reasoning behind regulations rather than simply memorizing answers. The ability to apply regulatory knowledge to various scenarios demonstrates deeper comprehension and improves performance on scenario-based test questions. I focused on understanding the safety principles underlying each rule during my preparation just to build a solid foundation for decision-making on the exam. This conceptual approach proved valuable when encountering unfamiliar question formats that required analytical thinking rather than rote recall of specific provisions from the manual.

Additional resources and support options

The Missouri Department of Revenue maintains an online portal with updated information about licensing requirements,testing procedures, and application processes. Applicants can access forms,fee schedules, and contact information through the official state website from any location with internet access. I reviewed the online resources before visiting the testing office just to ensure I had current information about requirements and procedures. The website is regularly updated to reflect regulatory changes and policy modifications, making it a reliable source for accurate details about the licensing process. Various commercial driving schools operate throughout the state, offering structured training programs for prospective CDL holders. These programs range from intensive short courses to comprehensive long-term curricula depending on individual needs and scheduling preferences. I compared several training options before selecting a program that aligned with my learning style and timeline. The evaluation process involved reviewing curriculum content,instructor qualifications,pass rates, and job placement assistance to ensure the chosen program would provide the preparation needed for successful licensing. Scholarship opportunities may be available through state workforce development programs for eligible applicants seeking to enter the commercial driving profession. These financial assistance options can help reduce the cost of training and testing for qualified individuals who meet program criteria. I inquired about scholarship eligibility through my local workforce development office just to explore potential funding sources for my education. The representative provided information about available grants,training subsidies, and employment incentive programs that could offset the expenses associated with obtaining a commercial driver license.

Industry associations and veteran organizations sometimes provide support resources for individuals pursuing CDL certification. These groups may offer study materials,mentoring opportunities,or networking connections with experienced commercial drivers in the region. I reached out to a veterans affairs liaison just to learn about resources available to former military personnel seeking commercial driving careers. The contact provided information about specialized training programs,endorsement credit possibilities, and employer partnerships that value military experience in the commercial transportation sector. This connection opened doors to opportunities that might have been difficult to identify independently. Online forums and discussion boards dedicated to commercial driving can provide peer support and practical advice from experienced drivers. These communities often share study tips,test experiences, and job market insights that complement formal training materials. I participated in an online forum just to connect with other applicants and learn from their experiences navigating the licensing process. The discussions provided realistic perspectives on challenges, successes, and strategies that helped shape my approach to preparation and testing. This peer guidance supplemented the official materials and enriched my understanding of the profession beyond textbook knowledge. Employer-sponsored training programs may offer funded education opportunities for candidates committed to working for the sponsoring company after licensing. These arrangements typically involve tuition assistance in exchange for a service commitment upon completion of training and receipt of the CDL. I evaluated an employer partnership opportunity with a regional carrier just to understand the terms and obligations involved in such an arrangement. The discussion clarified the financial benefits,training schedule, and employment expectations associated with the sponsored program, allowing me to assess whether this path aligned with my career objectives and personal circumstances.

Final thoughts on preparation and testing

Success on the Missouri CDL permit test depends primarily on thorough preparation using current official materials and adequate time for study. The state provides the necessary resources freely, and many applicants pass on their first attempt when they approach the preparation with discipline and focus. I maintained a consistent study schedule, reviewed the manual multiple times, and practiced with sample questions just to build the knowledge base required for successful testing. This systematic approach resulted in passing all required sections without difficulty and set a strong foundation for the subsequent skills training phase. The journey from permit to full commercial driver license involves multiple steps, each building upon the knowledge and skills developed in the previous phase. Proper preparation at each stage contributes to overall success and helps establish the habits necessary for safe professional driving. I approached each requirement methodically, ensuring mastery before progressing to the next level of the licensing process. This gradual advancement allowed me to develop competence and confidence progressively, resulting in successful completion of all testing requirements and eventual receipt of my commercial driver license. Understanding the regulatory framework governing commercial vehicle operation is essential for both test success and safe driving practice. The rules exist to protect all road users and ensure consistent standards for professional drivers across the state and nation. I studied the regulations with attention to the safety principles behind each requirement, recognizing that compliance serves a purpose beyond merely passing an examination. This perspective made the learning process more meaningful and helped me internalize the knowledge needed for both the test and actual driving responsibilities as a commercial motor vehicle operator.