The zero
Capture the opposing zero to win.
Math chess
A Vietnamese strategy game combining chess and arithmetic. Every piece carries a number; use calculations to capture.
No one is playing yet0 waiting rooms
Movement
A nonzero piece moves at most its number horizontally, vertically or diagonally along a clear line.
Addition
Use the units digit of the sum of your piece and its adjacent support.
Subtraction
Subtract the support from the moving piece (A − B); only a positive result can capture.
Multiplication
Use the units digit of the product.
Division
A valid quotient or remainder can create a capture.
Read the full guide
Board setup, special rules and winning conditions for Math chess.
Vũ Văn Bảy's game · 9 × 11 board. Select a piece and a legal destination; choose a calculation when several captures are possible.
A quick guide to Math chess
Read the Math chess rulesWhat is Math chess?
Vietnamese Math Chess uses a 9×11 board and ten numbered pieces per side, from 0 to 9. Zero stays still. Arithmetic determines capture distances using a neighbouring friendly support piece; capturing the opposing zero wins.
How is capture distance counted in Vietnamese Math Chess?
From the supporting piece, not the attacker. Place the attacker directly behind a friendly support, calculate with the two numbers, then count that many squares beyond the support. The attacker jumps the support and replaces the enemy piece there; its number does not matter.
How does subtraction work in Math Chess?
Subtract the support from the attacker (A − B). Only a positive result gives a capture distance, so an attacker 7 behind a support 4 can capture at distance 3, but a 4 behind a 7 cannot capture by subtraction.
Does the higher captured score win Math Chess?
No. On ChessPlayX you win by capturing your opponent's zero, or when your opponent has no legal move. The captured-point total is shown only for information. The same position occurring three times with the same player to move is a draw.
How can I play with a friend?
Share one device for a local game, or choose the friend option above to create an online room and send its invitation. Online games need an internet connection. Local games are saved in this browser.
Play Math chess on one deviceWhich rules apply here?
Vũ Văn Bảy Math Chess · capture-zero mode. Read the setup, legal moves, special rules and end conditions before starting. The guide describes the variant used on ChessPlayX, including differences from other versions where relevant.
Read the Math chess rules