Cross Math

Cross Math is one of the puzzles on Logic Puzzles Online, a free site with sudoku, Queens, minesweeper, nonograms and other grid puzzles that plays in the browser without an account. The site offers it in English and in eight other languages.

A Cross Math grid looks like a small crossword whose words are sums. The plus, minus, times and divide signs and the equals signs are fixed, and so are the results; the empty cells take digits. Rows are read left to right and columns top to bottom, and the puzzle is solved when every equation in the grid checks out.

Each day the page offers a Daily puzzle with a countdown to the next one, next to separate Easy, Medium and Hard grids you can play as often as you like. Because each digit sits in a row and a column at once, a single placement often settles a second equation, so solving goes from the lines with one gap outwards.

The same maker's free Logic Puzzles app for iPhone carries Cross Math among its daily games, with streaks and hints, for players who want it on a phone as an app.

It suits players who like Nerdle or KenKen and want an arithmetic puzzle that is all deduction and no guessing, at a length that fits a coffee break.