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WikipediaSo, most know how to tell if something is divisible by 2 or 5, and many know how to tell if something is divisible by 9. What about other numbers?

So, here are strategies for discovering divisibility from 2 to 10, and then we'll talk about some rarer, more surprising divisibility tricks:

Divisible by two:If the number ends in 0, 2, 4, 6, or 8, it is divisible by 2.

Divisible by five:If the number ends in 0 or 5, it is divisible by 5.

Divisible by ten:If the number ends in 0, it is divisible by 10.

Divisible by nine: If you add all the digits in a number together and that new number is divisible by 9, then it is also divisible by 9.

Example #1: 189 -> 1 + 8 + 9 = 18, 18 is divisible by 9, so 189 is also divisible by 9

Example #2: 137781 -> 1 + 3 + 7 + 7 + 8 + 1 = 27, 27 is divisible by 9, so 137781 is also divisible by 9

(Note: If adding six numbers together in your head seems difficult, look for my next post on number-grouping tricks. Soon, adding six numbe…

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