Every line has to add up.

A crossword made of equations. Drop the right numbers into the gaps so every row and every column comes out true.

Free on Android. Plays offline, no account needed.

Try it: tap a gap, then a number.

Hints that show their working

Stuck? A hint fills one square and tells you which line it used, so you learn the move instead of just getting the answer.

“This row reads 4 × ? = 20, so the missing number is 5.”

Twenty-five chapters, from gentle sums to dense Master boards. Each level adds a little: one more equation, bigger numbers, fewer givens.

If your answer makes every equation true, it counts. There's no single “correct” layout to guess.

A fresh daily puzzle gets harder through the week. Check in each day for coins, and keep the streak going for the biggest reward on day seven.

Want no pressure at all? Zen mode has no timer and no mistake count.

Numbers press like calculator buttons. A soft chime when a line comes right, a little celebration when the board is done.

Light and dark themes, large numbers, and switches for sound and vibration.

The five-hundredth takes a little longer.