Quote:
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Originally Posted by Hydrae
All number divisible by 9 have the same symbol (so does 0).  |
And every time you follow those instructions, you end up with either 0 or a number divisible by 9, because every number divisible by 9 is x away from the next highest multiple of 10, with x being the number on the 10 spot, and the number in the one spot is y away from the next lowest multiple of 10.
example - 25.
18 is 2 away from 20 and 25 is 5 way from 20, so adding 2 and 5 equals 7, 25-7 is 18.
or
- 87
72 is 8 away from 80 and 87 is 7 away from 80, so adding 8 and 7 equals 15, 87-15 is 72.