Prime Numbers


A prime number is a number whose only factors are 1 and itself and where those two numbers are dissimilar. In simple words, prime numbers have only two factors i.e. itself and the number 1.

It also shows that the number 1 is not prime. 2,3,5,7,11 are the first five and most common prime numbers. Though it’s not necessary that all the prime number questions are only related to these five prime numbers. Among them 2 is the most special prime number. The reason is that it is the smallest and the only even prime number. If any question on SAT ask you to try a few options to determine the answer, you must try 2.

Have a look on the following statement.

  • The product of two prime numbers is always:
    (A) odd
    (B) even
    (C) a prime number
    (D) a number with only four factors
    (E) It cannot be determined from the provided information.

In case, you forgot that 2 is the prime number, you can try combination of all the other prime numbers and you will be most probably left with (B) and (D) answer choices. But if you try 2, option (B) will be eliminated and you will be left with only (D) which is the right answer.