Paul Nicholsen

# Easy Divisibility Tricks

Figuring out the factors of bigger numbers can be tough sometimes, but there are tricks to make your life a lot easier! You probably already know some of them, but I bet some are new!

**2**: If a number is even, it is divisible by 2. And the whole number is even if the last digit is even, i.e., a 0, 2, 4, 6, or 8.

ex: Is 3,576 divisible by 2?

The last digit is 6, which is even. The whole number is even.

**3**: A number is divisible by 3 if the __sum of the digits__ is divisible by 3.

ex: Is 495,321 divisible by 3?

4 + 9 + 5 + 3 + 2 + 1 = 24

24 is divisible by 3, so 495,321 is divisible by 3.

**4**: If the *last two digits *of the number are divisible by 4, the whole number is.

ex: Is 4,829,528 divisible by 4?

28 is divisible by 4, so 4,829,528 is divisible by 4.

**5**: If the number ends in a 5 or a 0, the number is divisible by 5

**6**: If the number has both 2 *and* 3 as factors, then the number is divisible by 6. (Bonus: Figure out why this is true!)

ex: Is 5,436 divisible by 6?

5,436 has 2 as a factor (ends with an even number)

5,436 has 3 as a factor (5 + 4 + 3 + 6 = 18, 18 is divisible by 3)

So 5,436 is divisible by 6

**7**: Sorry. No good trick for 7. You’ll just have to divide it out.

**8**: If the *last three digits* are divisible by 8, the whole number is divisible by 8.

ex: Is 72,240 divisible by 8?

240 is divisible by 8, so 72,240 is divisible by 8

**9**: If the sum of the digits is divisible by 9, then the whole number is divisible by 9 (similar to the threes trick)

ex: Is 75,933 divisible by 9?

7 + 5 + 9 + 3 + 3 = 27

27 is divisible by 9, so 75,933 is divisible by 9.

**10**: If the number ends in a zero, it’s divisible by 10.