1. Divisibility Tests How can you tell quickly whether a number can be divided exactly by another?

2. What does DIVISIBLE mean? A number is DIVISIBLE by another number if there is no remainder after division. The result after division is a whole number and the remainder is zero. eg 36 divided by 12 is 3, so we say “36 is divisible by 12”

3. DIVISIBILITY TESTS Divisibility by 2: Numbers that end in 0, 2, 4, 6 or 8 can be divided exactly by 2. They are said to be divisible by 2, and are also called EVEN numbers. Numbers that are not even are called ODD.

4. DIVISIBILITY TESTS Divisibility by 3: To test for divisibility by 3 (without actually doing the division), add all the digits together and if the sum is divisible by 3, then the original number is too. This is a “divisibility test for 3”.

5. DIVISIBILITY TESTS Divisibility by 4: A number is divisible by 4 if its last two digits can be divided by 4. Can you explain why this is so?

6. DIVISIBILITY TESTS Divisibility by 5: How can you tell by looking at a whole number if it can be divided by 5? State a “divisibility test for 5”.

7. DIVISIBILITY TESTS Divisibility by 6: A number that can be divided by 6 needs to be able to be divided by both 2 and 3. Now state a “divisibility test for 6”.

8. DIVISIBILITY TESTS Divisibility by 11 and others: Find out about other “divisibility” tests – eg by 11.

9. DIVISIBILITY TESTS Let’s test a number eg 120 2? Yes, because it ends in 0, so is even 3? Yes, because 1 + 2 + 3 = 6, which of course is divisible by 3! 4? Yes, because 20 can be divided by 4 5? Yes, because it ends in 5 or 0. 6? Yes, because it can be divided by 2 and by 3.

10. Test all the numbers on this page for divisibility by 2, 3, 4, 5, and 6. Remember some may be divisible by more than one of these numbers and some may not be divisible by any of them! 240 27 256 81 711 400 111 415 91 23 108 50 343 180 Write down your answers!