Originally Posted by LSLGuy
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As has been said, it all starts from the fact that all 2 digit numbers are actually in the form of 10a+b. So as long as you hide a multiply by 10 and a single addition in amongst a bunch of donothing steps you've got a working puzzle. e.g. take a digit, add 3 then double the result, then subtract 6, then divide by 2. Magically the same digit pops out. etc.
