Question

1. Hannah gives clues about her 6 digit secret number:

Answer 1

1.  This is a rule which helps a person identify if a number is divisible by nine.
There is no specific answer to why this is observed but I believe that is just how multiples of nine and three behave!

It is the same with the multiples of three as well!

By the way the 6 digit number could be 513315
thanks, hope that helps!!