Is 100 divisible by 8

Answer 1

No.

To test if a number is divisible by 8:

* first all multiples of 8 are even, so the number must be even;

* then: add 4 times the hundreds digit to twice the tens digit to the ones digit - if this sum is divisible by 8, then so is the original number.

As the test can be applied to the sum, repeating this summing until a single digit remains, only if this single digit is 8 is the original number divisible by 8.

For 100: 4x1 + 2x0 + 0 = 4 which is not 8, so 100 is not divisible by 8.