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.
2 + 3 + 0 + 4 = 9
So 2304 is divisible by 9.
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!!
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