Math Game Monday: Countdown

This game helps students develop strategic thinking while practicing their subtraction skills.

Many parents remember struggling to learn math. We hope to provide a better experience for our children. And one of the best ways for children to enjoy learning is through hands-on play.

So what are you waiting for? Let’s play some math!

Countdown

Math Concepts: subtraction within one hundred, thinking ahead.

Players: best for two.

Equipment: a hundred chart, penny or other token to mark your place.

Set-Up

The 23-page printable (pdf) Number Game Printables Pack file includes hundred charts, graph paper, and game boards from the first two Math You Can Play books.

Print your choice of hundred chart for players to share.

How to Play

Start with the penny on one hundred (or ninety-nine, if you prefer the 0–99 chart). The first player subtracts any amount from one to ninety-nine (ninety-eight on the alternate chart) and moves the penny to the new number.

On each succeeding turn, players subtract any amount from one up to twice as much as the previous move — but keep in mind that your opponent will then be able to subtract up to twice as much as you do.

The player who gets to zero wins the game.

Variations

The Calendar Game: The first player says any date in January. Then each player in turn increases either the month or the day (but never both at once) and says a new date later in the year. Whoever says December 31 loses the game.

History

Countdown can also be called Fibonacci Nim. It was originally described by M. J. Whinihan and is included in the book Winning Ways for Your Mathematical Plays, Volume 4, by Elwyn R. Berlekamp, John H. Conway, and Richard K. Guy. I discovered it in an online lesson by Geoff Patterson.

Jim Pardun shared the Calendar Game in a comment on Dan Meyer’s Tiny Math Games blog post.