Kakuro techniques

Every Kakuro puzzle can be finished without guessing, using a handful of named techniques. These are the seven, in the order they are worth learning. Kakuro by Splash Logic teaches them one at a time, in the same order.

By Splash Logic · Updated 20 September 2026

1. Magic sums

A total that can be made in only one way.

Some totals leave no choice at all. Three squares adding to 6 can only be 1, 2 and 3. Two squares adding to 17 can only be 8 and 9. These lines are the crowbars of a Kakuro board: you may not know the order yet, but you know every digit involved.

When to look for it: Scan a new board for the shortest lines with the smallest or largest totals, and start there.

2. No repeats

A digit can appear only once in a line.

The second rule does more work than it looks. It removes 2 + 2 for a total of 4, it makes 20 in three squares impossible to build from three 6s and 8s, and once a line already contains a 3, every other square in that line loses the option of a 3.

When to look for it: Whenever you write a digit, look along both of its lines and cross that digit off the rest.

3. Cross-referencing

Use a row and a column together on the square where they meet.

Every white square belongs to two lines at once. If the row allows 1, 3 or 5 there, and the column allows 5 or 6, the square must be 5. This is the technique that turns two vague lines into one certain digit, and it is how most boards get opened up.

When to look for it: When a line narrows to a few options, check what its crossing lines allow at each square.

4. Narrowing combinations

Keep only the digit sets that survive what you already know.

A total usually allows several sets of digits. Twenty-two in three squares can be 5+8+9 or 6+7+9. If you already know the line cannot contain a 5, only one set is left, and the line holds 6, 7 and 9 in some order. That is often enough to finish it.

When to look for it: Write the possible sets for a line in the margin, then delete sets as squares get filled.

5. Hidden pairs and singles

A digit that fits in only one square of a line.

Sometimes a digit has nowhere else to go. If a line must contain a 9 and only one of its squares can hold a 9, that square is a 9, even if it looked like it had several options. The pair version works the same way with two digits confined to two squares.

When to look for it: For each digit a line still needs, count how many of its squares could take it. If the answer is one, you have found it.

6. Naked pairs

Two squares that share the same two options.

If two squares in a line can each only be 4 or 7, then between them they use up the 4 and the 7. No other square in that line can be a 4 or a 7, even though you do not yet know which is which.

When to look for it: Look for two squares in a line with identical two-digit option lists, then clear those digits from the rest of the line.

7. Region sums

Compare the total of a block of lines with what it contains.

Take several rows that between them cover a block of the board, and add their clues. Then add the clues of the columns crossing that block. The difference tells you the value of the squares that stick out, which often pins a single square exactly.

When to look for it: Use it late, when a corner of the board resists everything else.

Where to go next

• The combinations table tells you every digit set behind these techniques.
• The rules, if you are new to Kakuro.