Name: Kelera If the sum of the digits of a number is divisible by 9, then the number itself it divisible by 9. Why is that? How do you explain this? Hi Kelera,I think that this is easiest to explain using an example. Suppose that the number is 5634. Then
Thus if 5634 is divisible by 9 then, since (a multiple of 9) is divisible by 9 so is 5 + 6 + 3 + 4 Conversely if 5 + 6 + 3 + 4 is divisible by 9 then, since (a multiple of 9) is divisible by 9 so is 5634. Cheers,Penny
