SepoGamesWhat is Kakuro?
Kakuro is a number puzzle that looks like a crossword. But instead of words, you write digits. Each clue is a sum. Your job is to find which digits make that sum. That is why Kakuro is also called Cross Sums. You can play Kakuro online free here, with no download and no sign-up.
Kakuro rules
- Write one digit from 1 to 9 in every white square.
- A line of white squares is called a run. Each run has a clue in the dark square before it.
- The number in the top-right of a clue square is for the run going across (to the right).
- The number in the bottom-left is for the run going down.
- The digits in a run must add up to the clue.
- A digit may not repeat inside the same run. (It can repeat in other runs.)
- There is no 0. Every puzzle on this page has exactly one correct solution, checked by a computer.
How to use the buttons
- Easy / Medium / Hard – pick a size. Easy is 5×5, Medium 7×7, Hard 9×9.
- ◀ ▶ – go to the previous or next puzzle. Your progress is saved on this device.
- 1–9 – tap a white square, then a digit. On a keyboard, type the digit and use the arrow keys to move.
- ⌫ Erase – clear the square (or press Backspace).
- ✏️ Notes – write small pencil marks for digits you are not sure about (or press N).
- 💡 Hint – fills one correct digit. Hints are fine; your best time only counts without them.
- ✔ Check – marks wrong squares in red.
- ↺ Reset – start the puzzle again.
- The box under the board shows the sums for the selected square and all digit combos that fit. Combos that no longer work are crossed out. A clue turns green when its run is correct.
What Kakuro does for your mind
Kakuro is not a magic brain pill. But it is a good, honest workout for some everyday thinking skills:
- Logic. You never guess. You ask: "Which digits can make 23 in three squares?" The answer is only 6, 8 and 9. That is pure step-by-step reasoning.
- Mental arithmetic. You add and subtract small numbers again and again. It keeps simple maths quick and fresh.
- Working memory. You hold two runs in your head at the same time, the across and the down, and find the digit that fits both.
- Focus. One wrong digit breaks a whole run. The puzzle gently trains you to slow down and check.
- Planning. Good players look for the easiest square first. That habit, "start where the choices are fewest", helps in many real tasks.
- Patience and calm. A Kakuro has no timer pressure unless you want it. Many people use one puzzle as a quiet 10-minute break.
- A small win. Finishing a grid gives a real sense of achievement. That feeling is a nice reason to come back tomorrow.
What science says, honestly
Researchers at the University of Exeter and King's College London looked at more than 19,000 adults aged 50 and over in the online PROTECT study (papers in the International Journal of Geriatric Psychiatry, 2018 and 2019). People who did word and number puzzles more often scored better on tests of attention, reasoning and memory. Regular number-puzzle players did about as well on problem-solving tests as people around eight years younger. But the lead researcher was clear: "We can't say that playing these puzzles necessarily reduces the risk of dementia in later life." This is a link, not proof. Maybe puzzles help the brain, or maybe sharp people simply enjoy puzzles more. Play Kakuro because it is fun and keeps you thinking, not as a treatment.
Who is it for?
- Beginners and kids (about 9+): start with Easy. The runs are short and the combo box helps you learn.
- Daily players: one Medium grid is a good 10–15 minute habit, like a Daily Sudoku.
- Experts: Hard grids have long runs and need real chains of logic. Try them without notes or hints.
- Older players: big squares, no time limit and simple adding. It is a calm puzzle you can stop and continue later.
Kakuro tips and strategy
- Learn the "magic" sums. Some sums have only one combo. Two squares: 3 = 1+2, 4 = 1+3, 16 = 7+9, 17 = 8+9. Three squares: 6 = 1+2+3, 7 = 1+2+4, 23 = 6+8+9, 24 = 7+8+9.
- Start at the crossings. Find a square where an across run and a down run share very few possible digits. Often only one digit fits both.
- Use big and small limits. In "4 in two squares" no digit can be bigger than 3. In "17 in two squares" no digit can be smaller than 8.
- Count what is left. If a run of 15 already has 9, the other two squares must make 6 – without 9.
- Remember: no repeats. 4 in two squares can never be 2+2. It must be 1+3.
- Use notes on hard grids. Write the possible digits, then remove them as other runs fill in.
- Check green clues. When a clue turns green, that run is done. Use its digits to help the crossing runs.
- Print and practise. Our free printable Kakuro PDF has 6 puzzles (easy to hard) with answers on the last page.
Want a pencil-and-paper version? Download 6 printable Kakuro puzzles with answers – free, A4.
📄 Get the Kakuro PDFA short history of Kakuro
Kakuro started in America. In 1966, Jacob E. Funk, a Canadian working for Dell Magazines, created the English name Cross Sums. Later the puzzle became very popular in Japan, where the name Kakuro comes from "kasan kurosu" – addition cross. In the UK it first appeared in The Guardian, then in other newspapers.
Fun fact 1: In Japan, Kakuro was the most popular logic puzzle in print until Sudoku overtook it in 1992.
Fun fact 2: A nine-square run must always add up to 45, because it has to use every digit from 1 to 9 exactly once.
Questions people ask
Is Kakuro harder than Sudoku?
It is different. Sudoku uses only placement logic, while Kakuro adds simple adding and subtracting. Our Easy grids are small and gentle. The Hard grids have long runs and need more steps, so many players find them tougher than an average Sudoku.
Do I have to guess in Kakuro?
No. Every puzzle on this page was checked by a computer and has exactly one solution. There is always a next step you can find with logic, often by looking at a square where two runs cross.
What do the two numbers in a clue square mean?
The number in the top-right is the sum for the run going across to the right. The number in the bottom-left is the sum for the run going down. A clue square can have one or both.
Is Kakuro good for your brain?
It practises logic, mental arithmetic, focus and working memory. Large studies found that adults who often do number puzzles tend to score better on thinking tests, but that is a link, not proof that puzzles protect the brain. Play it because it is fun and keeps you thinking.
Can I play Kakuro online free without download?
Yes. Kakuro on SepoGames runs in your browser on phone, tablet or computer. There is no sign-up, no download and no cost.
Does my progress save?
Yes. Your solved puzzles, best times and the puzzle you are working on are saved in your browser on this device. If you clear your browser data, the progress is reset.
Can I print Kakuro puzzles?
Yes. Download our free A4 PDF with 6 Kakuro puzzles from easy to hard. The answers are on the last page.
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