Step 1: First create a list of numbers from 2 to 100 as shown in the figure given below.Leave the number 1 as all prime numbers are greater than one. The following steps show how to find all the prime numbers up to 100 by Eratosthenes' method. It is an ancient method for finding all the prime numbers up to any given limit. We can find prime numbers in mathematics by using an ancient technique, that is, the sieve of Eratosthenes.