A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. The first six primes are 2, 3, 5, 7, 11, and 13. But why? What good are prime numbers?

## Prime Numbers

Since the dawn of electronic computing, programs for finding primes have been used as a test of the hardware.