The last digit of 100 is 0, so it is divisible by 5 and is therefore not prime.įor 100 to be a prime number, it would have been required that 100 has only two divisors, i.e., itself and 1.

The list of all positive divisors (i.e., the list of all integers that divide 100) is as follows: 1, 2, 4, 5, 10, 20, 25, 50, 100.įor 100 to be a prime number, it would have been required that 100 has only two divisors, i.e., itself and 1.Īctually, one can immediately see that 100 cannot be prime, because 5 is one of its divisors: indeed, a number ending with 0 or 5 has necessarily 5 among its divisors. It is possible to find out using mathematical methods whether a given integer is a prime number or not.įor 100, the answer is: No, 100 is not a prime number.