SEPTEMBER 2005

Set up a grid, as shown in the top diagram, with three silver coins on the left hand side and three coppers on the right (perhaps use 10p and 1p coins). Can you interchange the two groups of coins, as shown in the bottom diagram? The middle cell has to be left empty when you finish.

Coins are moved just in a forward direction. This means you have to move silver coins to the right and coppers to the left only. A move consists of moving a coin onto the adjacent vacant cell, or jumping over an adjacent coin onto the vacant cell immediately behind it.