21 Number Game
Take turns counting from 1 to 21. Choose 1, 2, or 3 numbers per turn. The player who says 21 loses!
Game Board
Number Sequence
Your Move
Game History
No moves yet
How to Play
- • Players take turns counting from 1 to 21
- • On each turn, choose to add 1, 2, or 3 numbers
- • Numbers must be consecutive (e.g., 1,2,3 or 4,5)
- • The player who says 21 loses the game
- • Think strategically to force your opponent to say 21
Game Statistics
About 21 Number Game
The 21 Number Game is a classic mathematical strategy game that challenges players to think several moves ahead. This interactive version features intelligent computer AI, comprehensive move tracking, and a clean interface that makes strategic thinking both accessible and engaging for players of all skill levels.
How to Play
Step 1: Start the Game
The game begins at 0. Players take turns adding 1, 2, or 3 consecutive numbers.
Step 2: Make Your Move
Choose to add 1, 2, or 3 numbers to the current count.
Step 3: Computer Responds
The computer makes its strategic move based on optimal play.
Step 4: Win or Lose
The player who reaches 21 loses the game.
Game Features
- Strategic Gameplay: Plan multiple moves ahead to force your opponent into losing positions
- Intelligent Computer AI: Computer plays optimally using mathematical strategy
- Visual Number Sequence: Clear display of the current number progression
- Move History: Complete record of all moves made during the game
- Real-time Feedback: Immediate visual and text feedback for all actions
- Game Statistics: Track current number, remaining numbers, and available moves
- Responsive Design: Play seamlessly on all devices
Strategic Thinking
Mathematical Strategy
Learn to identify winning and losing positions
Forward Planning
Develop skills to think several moves ahead
Pattern Recognition
Identify mathematical patterns and sequences
Risk Assessment
Evaluate the consequences of each move
Perfect For
- Students: Develop mathematical thinking and strategic planning skills
- Teachers: Use as an educational tool for mathematics and logic classes
- Parents: Engage children in fun, educational mathematical activities
- Puzzle Enthusiasts: Challenge strategic thinking and problem-solving abilities
- Game Theorists: Study optimal strategies and mathematical game theory
Winning Strategy
Key Positions
Learn to identify and create losing positions for your opponent
Modulo Strategy
Use modulo 4 arithmetic to determine optimal moves
Backward Induction
Work backwards from 21 to identify winning positions
Technical Implementation
Built with modern web technologies including React and TypeScript, the 21 Number Game provides a smooth, responsive experience. The game features intelligent computer AI using optimal mathematical strategy, comprehensive move tracking, and real-time game state management to ensure an engaging user experience.
Why Choose Our 21 Number Game?
Unlike simple counting games, our 21 Number Game provides intelligent computer opponents, comprehensive move history, and educational insights into mathematical strategy. With its clean interface, optimal AI, and detailed statistics, it's the perfect tool for developing strategic thinking and mathematical skills while having fun.
Start playing our 21 Number Game today and challenge yourself to improve your strategic thinking and mathematical skills. Whether you're a student learning mathematical concepts, a teacher seeking educational tools, or simply someone who enjoys strategic puzzles, this game provides an engaging and educational experience for everyone.