Understanding Prime Numbers
A Prime Number is a number that cannot be evenly divided by any other whole number other than 1 and itself. So 1, 2, 3 and 5 are all prime numbers, but 4 is not, since 4 can not only be divided by 1 and 4, but 2 as well.
A prime number is a number that is not evenly divisible by any number other than 1 or itself. So if we are asked to list all the prime numbers between 1 and 10, we could determine the answer by considering each number between 1 and 10, and determining whether it has any factors other than 1 and itself.
Essentially, any number that has an entry in the 'Other Factors' column is not a prime factor. So the prime numbers between 1 and 10 are 1, 2, 3, 5 and 7.
(Fun Fact: Did you know that '2' is the only even prime number?)