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## 'GOT IT Now' printed from http://nrich.maths.org/

The game
Got It is a version of a well known old favourite called
Nim.

It is an adding game for two. You play against the computer or
against a friend.

Start with a target of $23$. Set the range of available numbers
from $1$ to $5$.

Players take turns to add a whole number from $1$ to $5$ to the
running total.

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

Play the game several times. Can you always win?

Can you find a winning strategy?

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

Change the game, choose a new GOT IT! target.

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

Can you work out a winning strategy for any target?

Is it best to start the game? Always?

Change the game again, returning to a target of $23$ but using a
different range of numbers this time.

Test out the strategies you found earlier. Do they need
adapting?

Can you work out a winning strategy for any range of numbers? Is it
best to start the game? Always?

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

Extensions:

Can you play without writing anything down?

Target $24$ using either a $1$, $3$ or $5$. What is the strategy
now?

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

Play NIM.