The ASVAB is a series of tests developed by the Department of Defense and is used by the U.S. Army to determine whether you have the mental aptitude to enlist. The ASVAB also helps determine which Military Occupational Specialties (MOS) you qualify for. The ASVAB is required to enlist in the U.S. Army and is valid for two years. The ASVAB may be given in a computerized version at a Military Entrance Processing Station (MEPS) or in a paper version at various Military Entrance Test (MET) sites around the country or at high schools and colleges.
The ASVAB Career Exploration Program (CEP) , takes approximately three hours, covers eight subjects and is composed of 200 questions. The ASVAB CEP is currently a pen and paper test. If it is offered by their school, high school students can take the ASVAB CEP test in grades 10, 11 and 12. They can only take it at the high school they attend, unless special arrangements are made.
The President, Secretary of Defense and other senior executive officials are advised by a seven-member Joint Chiefs of Staff, which is headed by the Chairman of the Joint Chiefs of Staff, the highest-ranking officer in the United States military and the Vice Chairman of the Joint Chiefs of Staff. The rest of the body is composed of the heads of each of the DoD's service branches (the Chief of Staff of the Army, the Chief of Naval Operations, the Commandant of the Marine Corps and the Chief of Staff of the Air Force) as well as the Chief of the National Guard Bureau. Although commanding one of the five military branches, the Commandant of the Coast Guard is not a member of the Joint Chiefs of Staff. Despite being composed of the highest-ranking officers in each of the respective branches, the Joint Chiefs of Staff does not possess operational command authority. Rather, the Goldwater-Nichols Act charges them only with advisory power.
The four most important sections of the test—Word Knowledge, Paragraph Comprehension, Arithmetic Reasoning, and Mathematics Knowledge-make up your Armed Forces Qualifications Test (AFQT) score. Your AFQT score ranges from 0 to 100 and determines if you are able to enlist in the military and which jobs and programs you may qualify for when you are in.
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.
There have been attempts to produce a military strength index: this is an example taken from a Credit Suisse report in September 2015. The factors under consideration for that military strength indicator and their total weights were: number of active personnel in the army (5%), tanks (10%), attack helicopters (15%), aircraft (20%), aircraft carriers (25%), and submarines (25%). It was practically impossible to make an estimation of the actual training of the armed forces.  These were the results:
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.