Sumline: Cross Math Puzzle

Every row and every column is an equation. Fill the blanks so all of them are true at once.

Sumline is a cross math puzzle for people who finish the crossword. No timers forcing you, no lives to lose, no energy to wait for. Just a grid, a handful of number tiles, and one correct answer.

NO GUESSING. EVER.

Most math puzzle games eventually hand you a board that cannot be solved by reasoning, only by trying values until something fits. Sumline does not. Every one of the 4000 puzzles was checked by an independent solver before it shipped: exactly one solution, and always reachable by logic alone. If you are stuck, there is a cell you can work out. That is a guarantee, not a slogan.

HOW IT PLAYS

Tap a number tile, then tap a blank cell. Tap a filled cell to take the tile back. Every tile in the pool is used exactly once. Multiplication and division are calculated before addition and subtraction, and division always comes out exact, with no fractions and no remainders.

FOUR DIFFICULTIES

Easy, Medium, Hard and Expert, on grids from 3x3 up to 5x5. Easy is a quiet few minutes. Expert is a genuine number puzzle with nineteen blanks and no obvious first move.

HINTS THAT TEACH

A hint does not just fill in the answer. First it points at the line worth looking at. Then it names the reasoning that solves it. Only then does it place the tile. If you have put something wrong on the board, it tells you so without costing you a hint, and offers to take you back to the last working position.

WHAT IS NOT IN HERE

No subscription. No lives or hearts. No daily energy. No account to create. No internet needed to play. The whole game works offline, on a plane, on the subway, anywhere.

A one time purchase removes ads and gives unlimited hints. That is the only thing sold, and it is optional.

FOR PEOPLE WHO LIKE

Sudoku, kakuro, killer sudoku, crossword puzzles, logic puzzles, brain training, mental math, arithmetic, number games and quiet thinking.

Sumline is made by one person. If something is wrong or a puzzle feels broken, write and it gets fixed.