Score
0
Time
150s
Best
—
Cross-sums logic puzzle. Fill the white cells with 1–9 so every run has no repeats and adds up to its clue. Solve as many as you can in 150 seconds.
Tap a white cell to select it, then tap a digit on the keypad to place it. The ⌫ key clears the selected cell.
The black cells carry the clues. A number in the top-right corner is the sum for the run going right; a number in the bottom-left corner is the sum for the run going down. A run is a straight line of white cells between two black cells.
Two rules apply to every run: the digits must add up exactly to its clue, and no digit may repeat within the same run. A cell turns red when a full run misses its sum or a number appears twice in one line, so mistakes are easy to spot.
Complete a grid to score a point and a new puzzle appears instantly. Solve as many as you can before the timer runs out.
Memorise the magic combinations — the runs that can be filled only one way. Two cells summing to 3 must be 1 and 2; summing to 4 must be 1 and 3; 16 must be 7 and 9; 17 must be 8 and 9. Three cells summing to 6 are 1, 2 and 3; summing to 24 are 7, 8 and 9. Whenever a clue forces a unique set of digits, you have a foothold before you even glance at the crossings.
Work the intersections. Every white cell sits where one across run and one down run cross, so the digit you write must belong to both clues' possible sets. If an across run can only hold {1,2,3} and the down run through one of its cells can only hold {3,8,9}, that shared cell must be 3. Hunting for these overlaps cracks far more cells than guessing ever will.
Use the no-repeat rule as hard as the sum. A long run with a large total still cannot reuse a digit, so a five-cell run cannot be built from small numbers alone. Checking the minimum and maximum a run can reach tells you instantly whether a candidate digit even fits before you commit to it.
In the timed mode, start with the shortest runs and the most extreme clues, because those pin digits with the least work. Place every forced number first, let the crossings cascade, and only then resolve the looser middle cells. A red cell shows up within a tap or two of a wrong move, so back it out and keep a clean board rather than racing into a tangle.