How to play
- Choose a board, rule mode, and opponent.
- On each turn, pick exactly one non-empty row.
- Take at least one ninja from that row.
- In the main rule, the player who removes the final ninja wins.
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Take Away
A Samurai Sums version of Nim for subtraction, comparison, and strategy. Choose one row, take away ninjas, and try to leave your opponent the board nobody wants.
SubtractionComparisonStrategyPatterns
Strategy and subtraction
Take away ninjas. Control the finish.
Choose one row, remove some ninjas, and try to leave your opponent the board nobody wants.
Fastest win-0 games played
Game settings
Classic 3, 5, 7The classic three-row Nim board.
The player who removes the final ninja wins.
Classroom instructions
- 1. Choose exactly one row on your turn.
- 2. Take at least one ninja from that row.
- 3. In the main rule, the player who takes the final ninja wins.
- 4. Safe boards leave your opponent without a winning strategy if you keep playing accurately.
Keyboard play
Use Up and Down to change row, Left and Right to change the take, number keys for amounts, and Enter to confirm.
Take Away guide
How Take Away supports maths practice
Take Away is a Samurai Sums version of Nim. Learners remove ninjas from one row at a time, practise subtraction, and learn how safe board states can control the finish.
Skills practised
- Subtraction and counting down
- Comparing row totals
- Strategic reasoning
- Pattern spotting and safe board states
Teacher notes
- Works as a quick starter, paired strategy activity, or independent AI challenge.
- Ask pupils to explain what the board will look like after their move before confirming it.
- Use strategy hints to introduce the idea of leaving an opponent a safe board.