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comment by ooli
ooli  ·  3411 days ago  ·  link  ·    ·  parent  ·  post: Math fans of Hubski, it's Pi day! Share some math stuff for fun.

If you chose any 2 digit number; 71

And subtract it with the same 2 digit in reverse order:

71-17 =54

Then do it again

54-45=9

At one point You ALWAYS end up with 9 or 0

that the Kaprekar Constant it works for 3 and 4 digits always giving 495 and 6174 .. better than golden ratio in my book.