Divisibility Rules

We have been talking about prime numbers, composite numbers and factors.  When working on these ideas we found that students who knew the rules of divisibility were able to work out the factors of any given number or whether a number was prime or composite faster than those who didn't know the rules.

Check out the movies or read the info on these websites to clear up the Divisibility Rules Mystery and beat the others to the answers!

Divisibility rules for 3 and 9

Rules for 2, 3, 4, 5, 6, 9 and 10

Another movie with examples at this website

Can you find rules for 7 and 8?????