== Prime number: A natural number with only two natural factors, 1 and itself (e.g, 17 is a prime number since its only natural factors are 1 and 17.) 38 is not a prime because because its natural...
You can tell right away just by looking at it that it's divisible by 10. A number isn't prime if it's divisible by anything else besides '1' and itself, and we found another one right away, so we...