How to Calculate Prime Numbers
What is Prime Numbers?
A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself. Primes are the "atoms" of arithmetic — every integer greater than 1 can be written as a unique product of primes (fundamental theorem of arithmetic).
Step-by-Step Guide
- 1Check if the number is greater than 1
- 2Try dividing by every integer from 2 up to √n
- 3If none divide evenly, the number is prime
- 4If any divide evenly, it is composite (not prime)
Worked Examples
Input
17
Result
Prime
Not divisible by 2, 3
Input
51
Result
Composite
51 = 3 × 17
Input
97
Result
Prime
Not divisible by 2,3,5,7