Math CentralQuandaries & Queries


Question from Alex, a student:

List of Nine digit numbers, that can be divided by nine?

Hi Alex,
A couple steps testing if numbers are divisible by 9 may help you generate your list:

  1. Add all digits of your number

  2. If the sum of the digits is divisible by 9 then so is the original also is.

An nine digit example:
Since 9 is divisible by 9 we know that 111111111 is also.

If you choose digits that add to multiples of 9 (9,18,27,36,...), this will generate your list of nine digit numbers.


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