A prime number is defined by being a positive integer that has exactly two positive integer factors. One way of finding prime numbers is the process of, "Sieve of Eratosthenes."
You start with all numbers from 1-100.
Cross out 1 because it is not prime.
Circle two because it is the smallest even prime integer.
Cross out every multiple of 2 or every second number.
Circle 3 because it is the next prime number.
Cross out all the multiples of 3.
Circle the next open number (5).
Cross out the multiples of 5... and continue until you reach 100.
