Math Cross
Brain TrainingFree to playFill crossing arithmetic answers in a grid.
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How to Play
Math Cross fills only the middle row and middle column of the grid, and gives you two totals: what the row must add up to, and what the column must. Tap an empty cell, press a digit from 1 to 9, and get both sums right to solve the board. Three boards inside one 120-second clock.
Controls
- Select — Tap an empty cell
- Fill — Tap a digit on the keypad under the board, or press 0-9
- Clear — The Clear button, or Backspace
- Pause — P
Tips & Tricks
- 1Only the middle row and the middle column are playable, so the grid is a plus sign of cells and two arithmetic constraints. Everything else on screen is margin.
- 2The centre cell belongs to both sums. That makes it the single most expensive digit on the board: every value you put there moves the row and the column by the same amount, so it is decided by the gap between the two targets rather than by either one.
- 3Every digit is 1 to 9 with no repeats enforced, so the maximum a row of five can reach is 35 and the minimum 15. A target outside what the row length allows is not a hard puzzle, it is a mis-read clue.
- 4A digit placed scores a point whether or not it turns out right, so correcting a cell pays twice. Clearing with Backspace costs nothing but the time.
Frequently Asked Questions
When is a board solved?
When the middle row adds up to its clue and the middle column adds up to its own. Every empty cell in that plus shape has to hold a digit first, and a board that runs out of time is simply lost.
How many boards are there?
Three, growing in size, inside one 120-second clock that is not reset between them. Score is a point per digit placed, so a corrected cell counts twice and there is no penalty for a wrong digit.
Can I play on my phone?
Yes. Select a cell by tapping it, then tap a digit on the keypad under the board. Every digit is worth one point whenever it is placed, including a digit you later overwrite, so the keypad makes it easy to run the score up without solving anything — the puzzle only ends when both the across row and the down column are correct.
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