Registration for the ASVAB is done entirely through your local recruiter. They will not want to start the application process without being confident that you will be a qualified applicant, so they will first ask you some information about your age, fitness, and marital status, among other things. They will likely also administer a short practice exam before taking you to a testing center to either give you a realistic idea of which jobs you would qualify for or to help you decide if it would be better to study before taking it.
A good score on the ASVAB is different than a minimum required score.  Each of the military branches will have their own minimum required scores (see below).  In practice, however, each branch will be more selective in their recruiting.  A score of 50 on the ASVAB implies that you scored as well or better than 50% of comparable test-takers.  Since ASVAB scores are used for many purposes (e.g., enlistment eligibility, military job placements, and career exploration), it is important that you score well on the ASVAB.  A score of 60 or better should be your minimum target.
At this point, it should be clear that an ASVAB practice test is required. The next decision is regarding the people that should be trusted to provide the test. Well, that is undoubtedly the nation's practice tests. They have a team of men and women that thoroughly analyze all areas that are covered on the ASVAB test. In addition to that, those men and women examine previous test questions and implement those so that the user of the tests is provided with the most precise questions. Lastly, one can say based on the unequivocal evidence that individuals that prepare with these ASVAB practice tests excel.
By military department, $146.9 billion was allocated for the Department of the Army, $168.8 billion for the Department of the Navy, $161.8 billion for the Department of the Air Force and $102.8 billion for DoD-wide spending.[6] By function, $138.6 billion was requested for personnel, $244.4 billion for operations and maintenance, $118.9 billion for procurement, $69.0 billion for research and development, $1.3 billion for revolving and management funds, $6.9 billion for military construction and $1.3 billion for family housing.[6]
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. 

The ASVAB is one of the most widely used aptitude tests in the world. The intent of the ASVAB test battery is to assess a candidate's potential for future success in the U.S. Military. Because of the nature of the test, the ASVAB can also be used to give a candidate valuable information about both military and civilian career choices that they may be suited for.

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.
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.