5 coins, 5 movesContributed by Peter N. Jacobson
Five coins are laid out in a row, three quarters and two nickels, the nickels separated by the quarters [QnQnQ]. The object is to rearrange the coins, in exactly five moves, always moving an adjacent nickel and quarter only, such that the coins end up sorted together [QQQnn] with no intervening gaps. You may neither separate nor reverse the quarter-nickel pair you are moving and they must be moved adjacent to another coin on each move, keeping in the same line. When you learn how to do this well, you will find that you can show people the solution very quickly and they still won't be able to duplicate it. Note that you can start with a different pair on the first move, reversing with the second, or start in the opposite direction entirely to further confuse them. Always let them try a few times before demonstrating the solution again to give them a chance to forget the rhythm. Once smugly competent in the 5 coins puzzle, it will be time to attempt the reverse, or "return to go" in just 4 moves. Same rules.