You’ll need to bring valid identification (photo ID, SSN card) to be admitted into the ASVAB testing room. Arrive on time— you’ll be turned away and required to reschedule if you are late. Your recruiter may give you a ride to and from the session, but he/she is not permitted in the testing room. You will not need to bring a calculator for the test.
The Mechanical Comprehension section of the ASVAB practice test measures your understanding of basic mechanical principles and mechanisms. You may be asked why an intake valve on a pump opens when the piston goes down, or what direction friction is going when shown a diagram of a skier. The CAT-ASVAB has 16 questions in 20 minutes; the paper-and-pencil version has 25 questions in 19 minutes.
After adding so much information to the aptitude test, there was a bit of difficulty interpreting the test results. In addition to that, a vast majority of test takers were deemed as being under qualified based on their test results. This is why the percentile change was made. It ensured that a 50% actually correlated with a person doing better than 50% of the test takers. Those revisions have worked hand-in-hand with the preparation of the armed forces.
The way to prepare for this exam is study hard and then quiz yourself with plenty of practice ASVAB tests. Remember that the exam is identical for all branches, so an Army ASVAB practice test is exactly the same as an ASVAB practice test for the Navy. The most important components of the test are the ones that count towards the Armed Services Qualifications Test, or AFQT. These sections are Word Knowledge, Paragraph Comprehension, Arithmetic Reasoning, and Math Knowledge. For tips and strategies for success on these questions, be sure to review our article on ASVAB Test Prep.
The ASVAB also known as the Armed Services Vocational Aptitude Battery is a test that measures your aptitude which is how well you do something.  A common mistake by most people is thinking that it is a measure of you IQ. Many people either forget this or don’t know this and they get worked up about the exam.  Saying that, it is also important to take a ASVAB sample test to insure you know what type of questions will be asked.    Another thing to keep in mind is every person in the armed forces has to take the exam and you are not being called out to take it. 

It’s best to keep the contact information of your nearest recruiting office or your actual recruiter; they are your best bet for getting your scores. ASVAB scores are valid for up to two years before you need to retest so most offices will send your current scores via mail. If you can’t get yours by mail, you can pick them up from your local recruiting office.
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.
After adopting the test in 1976 the test became a way of indicating whether or not an individual was 100% qualified to serve. As previously mentioned this aptitude test has a colorful history. That is because it underwent a dramatic change in 2002 and another dramatic change in 2004. The change that occurred in 2002 expanded the categories of the test and the overall difficulty. This can be seen by the addition of all of the diverse categories below:
×