This game is taken from Martin Gardner’s 1975 Mathematical Carnival, pp. 15-16. Here is his description:

“Draw ten spots on a sheet of paper, spacing them so that when pennies or other tokens are placed on the spots, there will be some space between them. Number the positions one through ten.

The problem:

Remove one token to make a “hole”. Then reduce the tokens to a single token by jumping. No sliding moves are allowed. The jumps are as in checkers, over an adjacent token to an empty spot immediately beyond. The jumped token is removed. Note that jumps can be made in six directions: in either direction parallel with the base, and in either direction parallel with each of the triangle’s other two sides. As in checkers, a continuous chain of jumps counts as one “move”. After some trial-and-error tests one discovers that the puzzle is indeed solvable, but of course the recreational mathematician is not happy until he or she solves it in a minimum number of moves. Here, for example, is a solution in six moves after removal of the token on spot 2. (➔ indicates a jump.)

Remove token on spot 2 to make a hole. Now,

1. 7➔2
2. 9➔7
3. 1➔4
4. 7➔2
5. 6➔4, 4➔1, 1➔6
6. 10➔3 (the last token is on spot 3.)

(Try it on a triangular board!)

There is a better solution in five moves. Can the reader find it?”

After you try it for a while, below we give a five-move solution.

Remove token on 9 to make a hole. Now,

1. 7➔9
2. 10➔8
3. 2➔7➔9
4. 3➔8➔10➔3
5. 1➔6 (the last token is on spot 6)

Five moves!

Here are diagrams showing each of the five moves. We recommend you try it with the numbered triangle and ten tokens.

Five moves! That’s it!