Kakuro

Play kakuro free online

Kakuro is a crossword made of numbers. Instead of words, you write the digits 1 to 9 into the white squares, and instead of clues in a list, each line of white squares has a sum printed in the black square where it starts. Choose Easy, Medium or Hard. Every puzzle here has exactly one answer, and you can always reach it by reasoning: the computer works each one through before you see it, so you never have to guess. Nothing to sign up for, and a puzzle you start is saved in this browser.

Want the same puzzle as everyone else? Play the daily kakuro, a new one every day with a streak to keep. Stuck on a sum? The kakuro calculator lists every way to make it.

How to play

A run is a line of white squares across or down, from one black square to the next. The number in the black square at its start is its clue: above the diagonal for the run going across, below it for the run going down.

• Add up to the clue. The digits in a run add up to its clue.
• No repeats in a run. A digit appears at most once in each run, so 5 + 5 can never make 10. A two-square 10 is 1 + 9, 2 + 8, 3 + 7, 4 + 6.
• Only 1 to 9. There are no zeros.

Every white square belongs to one run across and one run down, and its digit has to work for both. That crossing is the whole game: a square where a two-square 16 (7 + 9) crosses a run that cannot hold a 9 must be 7. The guide to solving kakuro shows it step by step.

Controls

Tap a white square, then a number below the grid. Tap the same number again to clear it. Turn on Notes to jot small possible digits instead; writing a digit takes it out of the notes in its two runs for you. Erase clears a square and Undo takes back any move. The runs through the square you pick are shaded, and their clues light up.

With a keyboard, the arrow keys move between white squares, jumping over the black ones, and the number keys write. Hold Shift with a number to write a note, or press N to switch notes on and off. Backspace erases, U undoes and H asks for a hint.

Hint fills in one square and says why in a plain sentence; if one of your digits is wrong, it finds that first. Check marks in red any digit that is not right. A digit written twice in a run, or a run that already adds up to more than its clue, shows in red at once, and so does its clue.

Easy, medium and hard kakuro

• Easy puzzles are 6 by 6 squares with short runs. Each square can be settled by the sums of its two runs alone, so they are the place to learn.
• Medium puzzles are 8 by 8. Expect to notice that a run must hold a certain digit, and that only one of its squares can take it.
• Hard puzzles are 9 by 9, with longer runs. You will need to think about every way a run can be filled, in pairs and threes.

At every level there is one answer and a way to reach it without guessing. The daily kakuro changes level through the week.

Sums worth knowing

Some sums can be made only one way, and they are the best places to start. These are all of them for runs of two to four squares:

The pattern: the smallest and largest sums for each length, and the next one in from each end, are made only one way. For every length and sum, use the kakuro calculator and combinations chart.

What is kakuro?

Kakuro began in American puzzle magazines as “Cross Sums”, then found a second home in Japan, where the publisher Nikoli shortened its Japanese name, kasan kurosu (“addition cross”), to kakuro. Like sudoku, it spread around the world through newspapers in the 2000s. It needs only small sums, and many people find the steady click of runs settling into place a calming way to spend twenty minutes.