Question

Is 2,340 divisible by 90? How do you know?

Answer 1

Yes

Explanation:

`2340` ends with a `0`, so it is divisible by `10`

You can tell whether a number is divisible by `9` based on whether the sum of its digits is divisible by `9`.

`2+3+4+0 = 9` is divisible by `9`, so `2340` is divisible by `9`

`10` and `9` have no common factor greater than `1`, so `2340` must be divisible by `10 xx 9 = 90`