Chemistry! Hooray!

Chemistry! Hooray!

Wednesday 18 September 2013

Grade 8 Math Divisibility Rules


Divisibility by:


2If the last digit is even, the number is divisible by 2.
3If the sum of the digits is divisible by 3, the number is also.
4If the last two digits form a number divisible by 4, the number is also.
5If the last digit is a 5 or a 0, the number is divisible by 5.
6If the number is divisible by both 3 and 2, it is also divisible by 6.
7
 
Take the last digit, double it, and subtract it from the rest of the number;
if the answer is divisible by 7 (including 0), then the number is also.
8
 
If the last three digits form a number divisible by 8,
then so is the whole number.
9If the sum of the digits is divisible by 9, the number is also.
10If the number ends in 0, it is divisible by 10.
11Alternately add and subtract the digits from left to right. (You can think of the first digit as being 'added' to zero.)
If the result (including 0) is divisible by 11, the number is also.
Example: to see whether 365167484 is divisible by 11, start by subtracting:
[0+]3-6+5-1+6-7+4-8+4 = 0; therefore 365167484 is divisible by 11.
12If the number is divisible by both 3 and 4, it is also divisible by 12.


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