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- Introduction

Instead of actually carrying out a division, it is possible to "test" a number to see if it can be divided exactly by certain numbers.

If a number divides exactly into a number, it is divisible by this number.

24 is divisible by 2, because 24 ÷ 2 is a whole number.

24 is not divisible by 5, because 24 ÷ 5 is not a whole number.

Here are the rules to test divisibility by 2, 3, 5 and 10.

__Rule for 2__

A number is divisible by 2 if it ends in 0, 2, 4, 6 or 8.

This means that it is even.

__Rule for 3__

A number is divisible by 3 if the sum of its digits is divisible by 3

3045 is divisible by 3, because 3 + 0 + 4 + 5 = 12 which is divisible by 3

3044 is therefore not divisible by 3, because 11 is not divisible by 3.

**Rule for 5**

A number is divisible by 5 if it ends in 0 or 5.

3045 is divisible by 5, because it ends in 5.

3030 is divisible by 5, because it ends in 0.

5551 is not divisible by 5.

**Rule for 10**

A number is divisible by 10 if it ends in 0.

3140 is divisible by 10, because it ends in 0.

3145 is not divisible by 10.

**Example**

Is 3813 divisible by 3?

**Answer**

Yes, because 3 + 8 + 1 + 3 = 15, which is divisible by 3.