Quote:
Originally Posted by AustinChief
What trick? That any 2 digit number whose digits add up to 9 is also divisible by 9?
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More like the digits of the multiples of 9 from 1 to 10 add up to 9. Not really a trick, I guess. I think the back of my mind was also thinking about how transposed numbers are divisible by 9 when I wrote "trick".