NIM-ble Thinking Puzzle
The Puzzle:
 | The game of "NIM" involves rows of matches laid out to make a triangle. When it is your go, you must take one or more matches away BUT THEY ALL MUST COME FROM THE SAME ROW. |
You win if you force the other person to take the last match.
The diagram shows the game at the start and in mid-play. It is your go. Which match(es) should you take to win the game?
Then after three more moves your opponent takes the last match and you win!