Prime Numbers!

While some members of our class identified all the prime numbers up to 100, the rest of us completed a prime number investigation.

We discovered the following:

Prime numbers have only two factors.  One is not prime because it has one factor.

There are eight prime numbers up to 20 and 25 up to 100.  

The only even prime number is two.  

We also found a way to check if numbers were divisible by 3 by adding the digits. 

If numbers are not divisible by 2, 3 or 5, they must be prime (except for the three numbers 49, 77 and 91 which are divisible by 7).

Every even number between 2 and 50 is the sum of two prime numbers.