You have a simple (base-ten, whole number) calculator which can perform only two operations: visually reversing a number, and adding seven.

Prove that you can use this calcluator to convert any number to 1.

Notation: use ~ to denote reversal, as in
~53 = 35

(In reply to remarks: Not the most rigorous proof, but.... by Ady TZIDON)

ady wrote: "RE: ' Reverse the digits of N.' N was defined as an 1-digit number." 

Initially it was a 1-digit number, and then it keeps getting incremented by 7 at that LOOP.

:-)

Posted by Penny on 2004-02-23 02:11:20