In order to take the ASVAB at a MEPS for enlistment purposes, an individual will need to speak with a recruiter and schedule a time to take the test. ASVAB testing at a MEPS is self-paced and taken on a computer, and it may be retaken after a one-month waiting period.  Entitled the CAT-ASVAB, the test is adaptive – meaning it adapts to your ability level.
You are tested in four critical areas — Arithmetic Reasoning, Word Knowledge, Paragraph Comprehension and Mathematics Knowledge (see below) — these scores count towards your Armed Forces Qualifying Test (AFQT) score. The AFQT score determines whether you’re qualified to enlist in the U.S. military. Your scores in the other areas of the ASVAB determine how qualified you are for certain military specialties. Score high, and your chances of getting the specialty/job you want increase. The better score you get, the better chance you have of pursuing the specialty or field that you desire.
Achieving the minimum required AFQT score established by an individual branch gets your foot in the door, but the higher you score, the better. For example, if you need a medical or criminal history waiver in order to enlist, the military personnel who make those decisions are more likely to take a chance on you if they think you’re a pretty smart cookie.
What you'll learn: Cell biology, division and operations; genetics; evolution; plant and animal biology; nutrition; human anatomy and physiology; ecology; matter, atomic structure, the periodic table, and chemical reactions; measurement; nuclear chemistry; motion, force, energy, and work; fluids; waves and sound; and geology, meteorology, oceanography, and astronomy
Word Knowledge (WK), Paragraph Comprehension (PC), Arithmetic Reasoning (AR), and Mathematics Knowledge (MK). Scores on the AFQT are used to determine your eligibility for enlistment in the Army, Navy, Air Force, or Marine Corps. The other six test scores on the ASVAB tests are used to determine the best job for you in the military as your grades will demonstrate knowledge, skill, and interest in certain subjects and tasks. 
Personnel may be recruited or conscripted, depending on the system chosen by the state. Most military personnel are males; the minority proportion of female personnel varyies internationally (approximately 3% in India,[8] 10% in the UK,[9] 13% in Sweden,[10] 16% in the US,[11] and 27% in South Africa[12]). While two-thirds of states now recruit or conscript only adults, as of 2017 50 states still relied partly on children under the age of 18 (usually aged 16 or 17) to staff their armed forces.[13]

Candidates taking the ASVAB are given a AFQT (Armed Forces Qualifying Test) score which is simply a combination of your scores from four tests (Arithmetic Reasoning, Mathematics Knowledge, Word Knowledge, and Paragraph Comprehension). This AFQT score is represented as a percentile (from 1-99) which depicts how well you scored compared to other test takers. For example, if your score is a 57, this means that you scored better than 57% of the other test takers. The AFQT score is used to determine whether you are qualified to enlist in the U.S. Armed Forces.

One ASVAB sub-measure, the Armed Forces Qualification Test (AFQT)--which is just a separate analysis of the same tests that focuses only on four of the subtests--is also population-referenced, but its score from 1-99 is a percentile score. This means that if you score a 73, you scored as well as or higher than 73% of test-takers in the national sample.