Kakurasu Solver

Kakurasu Solver — Step by Step

Click a total on the right of a row or under a column and type it. Then press Solve. Or play a generated puzzle and send it here with one click.

Kakurasu Solver: rules, how to use it, tips

Shade squares so each row and column adds up to its total — a shaded square is worth its column number in its row and its row number in its column.

The columns are numbered 1, 2, 3… from the left, and the rows 1, 2, 3… from the top.
A shaded square adds its column number to its row’s total, and its row number to its column’s total.
Every row must add up to the number on its right, and every column to the number underneath.
Unshaded squares add nothing.

Choose the size, then click each total and type it (or press Sample).
Press Solve and step through: for each row or column, the sets of numbers that make its total, and what they all agree on.

Tiny and huge totals. A total of 1 or 2 has only one way to be made. A total of 1+2+…+N shades the whole line; one less than that leaves out only square 1.
List the sets. Write the ways to make a total: in a 6-wide row, 7 is 1+6, 2+5, 3+4, 1+2+4. Squares in every set are shaded; squares in none are empty.
Cross-check. A column that cannot use row 3 rules out every set for row 3 that uses that column.
Count from the top. The total of all row totals equals the total of all column totals’ partners — use it to check your copy.

The full guide, with a worked example and common mistakes: How to play Kakurasu.

What are the small numbers outside the grid?

Across the top: what a shaded square is worth in its row. Down the left: what it is worth in its column. Totals are on the right and at the bottom.

What maths does it practise?

Adding small numbers and finding all the ways to make a total — the same skill as number bonds and partitions.

Is there always one answer?

Yes — every puzzle here is checked to have exactly one solution.

How do I solve one from a book?

Open the Kakurasu Solver, type the totals and press Solve.