Turn Over Challenge

Can you solve it?

The Turn Over Puzzle

In the Turn Over Puzzle, ten two-sided objects (e.g., coins) are arranged in a circle.

At the start, all ten objects have the same side facing up (e.g., all Heads, if coins are used).

The object of the game is to turn nine of the objects upside down (e.g., to Tails) by following a simple set of rules.

While this may seem easy, most people find the challenge very difficult.

In the interactive version presented here, ten pieces from the board game Reversi (aka Othello) are used. These pieces are black on one side and white on the other.

At the start, all ten pieces show BLACK. You have to turn nine of the pieces over to show WHITE, leaving just one black piece at the end.

Can you find the solution?

Rules of the Challenge

  1. You must turn over NINE black pieces, so that they show white, leaving just one black piece at the end.

  2. For each turn, click FOUR pieces as you count 1-2-3-4 around the circle.

  3. Your count may include either black or white pieces at positions 2 and 3, but you must start and end each count on a BLACK piece. The black piece at count 4 is then turned over, to show white.

  4. You cannot jump over pieces.

  5. Each turn can start on ANY remaining black piece, and each count may go either clockwise or anti-clockwise.

  6. If you click a piece from which you cannot end your count, YOU LOSE!

Can you solve it?

Click the pieces to make your moves
or click DEMO to watch a demonstration
  Ten   Two  
Nine Can you turn over Three
Eight black pieces? Four
  Seven   Five  

About Turn Over Challenge

Turn Over Challenge is an interactive presentation by Michael Daniels of a puzzle described in Paul Daniels Adult Magic by Barry Murray (1989)