The following set of rules can help you save time in trying to check the divisibility of numbers.
|
A number is divisible by |
if |
|---|---|
|
2 |
it ends in 0, 2, 4, 6, or 8 |
|
3 |
the sum of its digits is divisible by 3 |
|
4 |
the number formed by the last two digits is divisible by 4 |
|
5 |
it ends in 0 or 5 |
|
6 |
it is divisible by 2 and 3 (use the rules for both) |
|
7 |
(no simple rule) |
|
8 |
the number formed by the last three digits is divisible by 8 |
|
9 |
the sum of its digits is divisible by 9 |
Example 1
-
Is 126 divisible by 3? Sum of digits = 9. Because 9 is divisible by 3, then 126 is divisible by 3.
-
Is 1,648 divisible by 4? Because 48 is divisible by 4, then 1,648 is divisible by 4.
-
Is 186 divisible by 6? Because 186 ends in 6, it is divisible by 2. Sum of digits = 15. Because 15 is divisible by 3, 186 is divisible by 3. 186 is divisible by 2 and 3; therefore, it is divisible by 6.
-
Is 2,488 divisible by 8? Because 488 is divisible by 8, then 2,488 is divisible by 8.
-
Is 2,853 divisible by 9? Sum of digits = 18. Because 18 is divisible by 9, then 2,853 is divisible by 9.