|Characteristic of number
||Number divisible by:
|Last digit is even
|The sum of the digits is divisible by 3
|The last two digits form a number divisible by 4
|The last digit is 0 or 5
|The number is divisible by both 2 and 3.
|To find out if a number is divisible by seven,
take the last digit, double it, and subtract it from the rest of the number.
If you get
an answer divisible by 7 (including zero), then the original number is divisible by seven.
If you don't know the new number's divisibility, you can apply the rule again.
to see if 203 is divisible by 7.
- double the last digit: 3 x 2 = 6
- subtract that from the rest of the number: 20 - 6 = 14.
- check to see if the difference is divisible by 7: 14 is divisible
by 7, therefore 203
|The last three digits form a number divisible by
|The sum of the digits is divisible by 9
|The numeral ends in 0
The (sum of the odd numbered digits) - (sum
of the even numbered digits) is divisible by 11.
Is divisible by 11
|The number is divisible by both 3 and 4.
|Delete the last digit from the number, then
subtract 9 times the deleted digit from the remaining number. If what is left is divisible
by 13, then so is the original number.
|The last four digits form a number divisible by
|TEST TIP: If a
number is divisible by two different prime numbers, then it is divisible by the products
of those two numbers. Since 36, is divisible by both 2 and 3, it is also divisible