## June 18, 2007

### 99 Cents Solved

Jacek has solved the 99 cent game - you can go read the comments on the previous post if you want to see the trick to winning it. Or just try playtesting Anthony's setup below to get a hint of the winning strategy without peeking.

These coin games are so great. On the second-to-last day of school Anthony had to bring a board game to play. Because of our move, all our board games were packed in boxes - and so he just brought a handful of change instead. No need for Parker Brothers if you want to play Nim or the 99 cent game.

Anthony does not yet know the secret for winning the 99 cent game, but I have taught the secret to Piper. Piper is only five, so she is just learning how to count up the value of coins. But when playing the game, she is utterly unbeatable - it is a remarkable thing to see.

Yesterday Anthony set up a "devious" set of coins to try to beat Piper - we had 75 cents in fourteen coins, and Anthony arranged them like this: (P is for a 1 cent penny, N is for a 5 cent nickel, and D is for a 10 cent dime)

`P D N D P D N N N P D P D P`

The wonderful thing about Anthony's setup is that when it is played, it looks like Piper is going to lose - until the very end!

Do you know any other cute games that can be played with a pocket full of coins?

Posted by David at June 18, 2007 12:21 PM

Actually, there are 13 coins in Anthony's setup

Posted by: at June 20, 2007 06:27 PM

Fixed - added the 14th coin.

Posted by: David at June 23, 2007 09:37 AM