Given the number 133, we list the first prime numbers and then look for a possible factor of 133:
Prime_list = {2, 3, 5, 7, 11, ...}
133 is not an even number, so we discard 2. 133 does not end with 0 or 5, so 5 can not be a factor. We evaluate 3, 7, and 11:
The only division with no rest is 133/7 = 19, and we know that 7 and 19 are prime numbers. We conclude that 133 is composite and can be represented as a product of 7 and 19:
