# Gord was looking at these multiples of 9: 18, 45, 63, 72, 81, 108, 216. He claimed that the sum of the digits in any multiple of 9 will add to 9. Do you agree or disagree? Justify your decision.

## What is your decision?

## I know it might sound stupid, but I said that I disagreed with him. The sum of the digits in any multiple of 9 will not add to 9, because the number will get bigger and bigger as the number that it multiplied by 9 gets bigger. F.E., 9x4=36. The sum of the digits is 9, and the times they've been multiplied by 9 is 4 times. Was I completely wrong?

## sorry, I meant the sum of the digits is 36 and not 9.

## 1+8=9

2+7=9

3+6=9

4+5=9

etc.

Keep going. What do you find?

## "sum of the digits is 36" -- 3 + 6 = 9

2 + 1 + 6 = 9

28 * 9 = 252

2 + 5 + 2 = 9

Can you think of any sum of the digits in any multiple of 9 that will NOT add to 9?

## Oh, multiple. I read it as multiply. I see why I'm wrong now, I kept thinking that the numbers have to be multiplied by 9, and not they have to be multiples of 9.

Thank you,

When I said "sum of the digits is 36", I had meant that 4x9=36 when I tried to offer an example. Though it makes sense that you reworded it, Thank you Ms. Sue and Writeacher once more.