The test must be completed if you wish to serve in the Army, Navy, Marines, Air Force, or Coast Guard. The test can also be taken as a career-exploration tool if you are a high school sophomore, junior, or senior. It takes approximately three hours to complete. If you take the computerized version of the test, results are given immediately. If you complete a paper and pencil test, you’ll get results within two weeks.
This advice, though well-intentioned, doesn’t address the needs of some new recruits who are interested in specific career fields but are worried about their test performance-especially in areas related to math comprehension. Potential recruits who feel deficient in math, language, or science skills should have a frank conversation with their recruiter to discuss possible refresher study or even supplemental classes in any self-perceived “problem areas” before taking the test.
After enlistment, new recruits undergo basic training (also known as "boot camp" in the Marine Corps, Navy and Coast Guard), followed by schooling in their primary Military Occupational Specialty (MOS), rating and Air Force Specialty Code (AFSC) at any of the numerous training facilities around the United States. Each branch conducts basic training differently. The Marine Corps send all non-infantry MOS's to an infantry skills course known as Marine Combat Training prior to their technical schools. Air Force Basic Military Training graduates attend Technical Training and are awarded their Air Force Specialty Code (AFSC) at the apprentice (3) skill level. All Army recruits undergo Basic Combat Training (BCT), followed by Advanced Individual Training (AIT), with the exceptions of cavalry scouts, infantry, armor, combat engineers and military police recruits who go to One Station Unit Training (OSUT), which combines BCT and AIT. The Navy sends its recruits to Recruit Training and then to "A" schools to earn a rating. The Coast Guard's recruits attend basic training and follow with an "A" school to earn a rating.
You can't use the AR and MK score shown on your ASVAB Score Sheet. The Score Sheet shows "number correct" for your AR and MK Scores, because "number correct" is what is used for job qualifications. However, the military does not use this same score when computing the AFQT. They use the "weighted scores" of the ASVAB sub-tests for AR and MK. Harder questions in these areas get more points than easier questions. The "weighted scores" for AR and WK are not listed on the ASVAB score sheet given to you after the test.
The scores from the other tests are used to determine what type of specialty you might be best suited for.  These "composite" scores (also known as line scores, MOS scores, or aptitude area scores) are calculated by adding together combinations of the different sub test standard scores. These composite scores are then used to determine which different military jobs (aka Military Occupational Specialties or MOS) may be the best fit for you.  Each branch of the military will have their own approach to these composite scores.
Mathematics Knowledge tests the ability to solve problems by applying knowledge of mathematical concepts and applications. The problems focus on concepts and algorithms, and involve number theory, numeration, algebraic operations and equations, geometry, measurement and probability. Mathematics Knowledge is one factor that characterizes mathematics comprehension; it also assesses logical thinking.