NRICH: Got It

Got It is an adding game for two players. You can play against the computer or with a friend. It is a version of a well known game called Nim.

Start with the Got It target 23.

The first player chooses a whole number from 1 to 4 .

Players take turns to add a whole number from 1 to 4 to the running total.

The player who hits the target of 23 wins the game.

Play the game several times.
Can you find a winning strategy?
Can you always win?

Does your strategy depend on whether or not you go first?

To change the game, choose a new Got It target or a new range of numbers to add on.

Test out the strategy you found earlier. Does it need adapting?

Can you work out a winning strategy for any target?
Can you work out a winning strategy for any range of numbers?

Is it best to start the game? Always?

Away from the computer, challenge your friends:
One of you names the target and range and lets the other player start.

Extensions:

Can you play without writing anything down?

Consider playing the game where a player CANNOT add the same number as that used previously by the opponent.

Age 7 to 14 

 


Addition & Subtraction
K-6, Middle School, High School

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NRICH (University of Cambridge)

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Online Game

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