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Sunday Times Teaser 3060 – Even and Odd

by Brian Gladman on May 14, 2021

by Edmund Marshall

Published Sunday May 16 2021 (link)

My daughter and I once played a game based on the number 13 and the following rule:

Think of a positive whole number greater than 1. If it is even, halve it. If it is odd multiply it by 13 and add 1. Either of these operations is to be regarded as one step. Apply another step to the outcome of the first step, and then further steps successively.

For our game, we chose different starting numbers that were odd, and the winner was the person who by the fewer number of steps reached the number 1. My daughter won because she started with the number that leads to 1 in the fewest number of steps.

What was my daughter’s starting number?

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One Comment Leave one →
  1. Brian Gladman permalink

    or we can start from 1 and run the process backwards

    Now modified to answer the extra puzzle posed by Jim Randell on his S2T2 site.

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