How to quickly test if a number is divisible by another number less or equal to 10

Sometimes you need to quickly find out if you can share something evenly between 2, 3, 4, 5, 6, 7, 8, 9, or 10 people. Then, do not do long division! Just follow these simple divisibility rules.

For example, a number is divisible by 3 if the sum of the digits of the number is divisible by 3.

Example #12

Can you share 4557 dollars evenly between you and your two sisters?

Since 4 + 5 + 5 + 7 = 9 + 12 = 21 and 21 is divisible by 3, then the answer is yes.