| Characteristic of number |
Number divisible by: |
| Last digit is even |
2 |
| The sum of the digits is divisible by 3 |
3 |
| The last two digits form a number divisible by 4 |
4 |
| The last digit is 0 or 5 |
5 |
| The number is divisible by both 2 and 3. |
6 |
| 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. |
7 |
Example: Check
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
is
also divisible
by 7.
|
| The last three digits form a number divisible by
8 |
8 |
| The sum of the digits is divisible by 9 |
9 |
| The numeral ends in 0 |
10 |
The (sum of the odd numbered digits) - (sum
of the even numbered digits) is divisible by 11.
Example:
34871903
3+8+1+0=12
4+7+9+3=23
23-12=11
Is divisible by 11 |
11 |
| The number is divisible by both 3 and 4. |
12 |
| 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. |
13 |
| The last four digits form a number divisible by
16 |
16 |
| 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
by 6. |
