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# Prime Number Formula

Prime Numbers are numbers that are divisible only by 1 and itself. A prime number cannot be factorized. The numbers that are not prime are called composite numbers. 1 is neither prime nor composite.

To calculate if a number is prime or not, we need to first find the factors of the number. A prime number has only 2 factors: 1 and the number itself. So, if the factors of the number is 1 and itself then it is a prime number. For example take a number 7. The factors of 7 is given as, 7 = 7 * 1. Since the number 7 has only two factors: 1 and 7 itself, it is a prime number.

 Related Calculators Calculate Prime Number Calculate Prime Factors Find Prime Factorization Calculator Prime Factorization Tree Calculator

## Prime Number Problems

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Some solved problems on prime number are given below:

### Solved Examples

Question 1: Find if 47 is a prime number or not ?
Solution:

The factors of 47 are 1 and 47.
So 47 is only divisible by 1 and 47.
So, 47 is a prime number.

Question 2: Is 16 a prime number or not ?
Solution:

The factors of 16 are 1, 2, 4, 8 and 16.
So 16 is not only divisible by 1 and 16 but also by 2, 4 and 8.
So 16 is not a prime number.
16 is a composite number.

*AP and SAT are registered trademarks of the College Board.