The Sum Game
Add numbers, claim squares, make a row before your rival!
About the Game
Two flags sit on a shared number line — say 5 to 15. Your first move places both flags; every turn after, you slide only one. The sum of wherever the two flags land gets claimed on a grid of every possible total. Get three of your claimed squares in a row to win the round, played best of three.
What Your Child Practices
Quick addition as the flags move and totals change turn to turn.
The same sum can come from more than one pair of addends, made visible by the shared, moving flags.
The slide-and-claim loop repeats every turn, building toward a three-in-a-row structure across rounds.
Planning a move that both extends your own line and blocks the opponent's at the same time.
Frequently asked questions
The Sum Game is tagged for Grades 1–8 — levels inside the game raise the difficulty further as your child improves.
The Sum Game is a 1v1 game — turn-based head-to-head, players alternate moves in one shared game.
No — The Sum Game plays directly in the browser, right on this page. No login, no download.
The same sum can come from more than one pair of addends, made visible by the shared, moving flags.
No — The Sum Game is free to play, no sign-up needed.