After a candidate has completed the ASVAB they must wait one calendar month before retaking the exam. An additional calendar month must pass before retesting a second time. Six calendar months must pass before retaking the test a third time. The scores received from the ASVAB may be used for enlistment for up to two years from the initial test date. 
The Assembling Objects section of the ASVAB practice test measures your ability to determine how an object will look when its parts are put together. You will be shown an illustration of pieces and asked to choose which one, among a selection of finished diagrams, shows how they fit together. The CAT-ASVAB has 16 questions in 16 minutes, while the paper-and-pencil version has 25 questions in 15 minutes.
My daughter bought this book to study for her ASVAB test. She took it the first time and did not get the score she needed. So she got this book to help her study and to raise her score. She took her test again and her score raised 14 points. I recommend this book to those that need help studying or need a higher score. The book has a lot of information about the test and has practice questions as well. Overall, the book is very useful for those who want to do well on the ASVAB.

Paragraph Comprehension tests the ability to obtain information from written material. Students read different types of passages of varying lengths and respond to questions based on information presented in each passage. Concepts include identifying stated and reworded facts, determining a sequence of events, drawing conclusions, identifying main ideas, determining the author's purpose and tone, and identifying style and technique.
The AFQT has been used in non-military settings as a proxy measure of intelligence, for example, in Herrnstein & Murray's book The Bell Curve. Because of the test's significance both inside and outside military settings, it is important to examine what the test measures, i.e. to evaluate the construct validity of the AFQT. Kaufman's 2010 review stated that David Marks (2010) scanned the literature for datasets containing test estimates for populations or groups taking both the AFQT and tests of literacy. One study on nine groups of soldiers differing in job and reading ability found a correlation of .96 between the AFQT and reading achievement (Sticht, Caylor, Kern, & Fox, 1972). Another study showed significant improvements among Black and Hispanic populations in their AFQT scores between 1980 and 1992 while Whites only showed a slight decrement (Kilburn, Hanser, & Klerman, 1998). Another study obtained reading scores for 17-year olds for those same ethnic groups and dates (Campbell et al., 2000) and found a correlation of .997 between reading scores and AFQT scores. This nearly perfect correlation was based on six pairs of data points from six independent population samples evaluated by two separate groups of investigators. According to Marks, "On the basis of the studies summarized here, there can be little doubt that the Armed Forces Qualifications Test is a measure of literacy." However, it is important to note that AFQT has been shown to correlate more highly with classic IQ tests than they do with one another, and that the "crystallized" intelligence measured by AFQT is measured very similarly by Wechsler, in particular.[8]
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.