Posted by Peter on 14th April 2010

Resource of the Week: Tests of divisibility

divisible-by-9-and-10This maths worksheet is another in our set on rules of divisibility. Knowing these rules will really help children in their maths up to the end of High School and beyond.

The rule for dividing by 10 is the easiest of them all:

If the whole number ends in a 0 then the number is divisible by 10.

The rule for 9 is also easy, but it does require a little adding up:

Add up all the digits. If the total of the digits is divisible by 9 then the whole number will be.

Example: 2304

2 + 3 + 0 + 4 = 9

So 2304 is divisible by 9.

Example: 9630

9 + 6 + 3 + 0 = 18

18 is divisible by 9 therefore 9630 is also divisible by 9.

The second part of the worksheet asks which numbers are divisible by both 9 and 10. Probably the best way to do this is to ignore any numbers that do not end in a zero, then add up the digits of the rest and see if they come to a multiple of 9.

If they do, and the last digit is a zero, then they are multiples of both 9 and 10. Easy!!

Divisible by 9 and 10

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