An Intelligence Quotient (IQ) test score of 70 or below does NOT cause you to have a mental disability. It is an indication of a mental disability based on the questions in the test and the answers provided by the person who took the test.

Only if you get the top score and add 10 to it. No valid IQ test can be given in 30 minutes, so I would be very suspect.

The highest score on the so called "Novis Mental Ability Test," is 155.

Many who have scored "off the scale" of a regular IQ test would test "low" on the Scientology created "Novis Mental Ability Test".

It is not even accepted for membership in any of the High IQ Societies (such as MENSA or The HI Q Society).

Yes, unless you develop a mental illness. However, your IQ test score can vary as it is imperfect.

your mental age (the age group that's average score is closest to yours in an IQ test)

divided by you physical age multiplied by 100

First, you take the test. It depends on how well you answered the test. By this I mean if you answered it like a 22 year-old that is your mental age. Then, you divide your mental age by your real age, next, you multiply that by 100.