How to play Cyfa
Cyfa is a daily number puzzle. You get six numbers and a few operators. Your job is to make zero, five different ways, as fast as you can. Everyone plays the same puzzle each day, and there is a new one at midnight.
Why it is called Cyfa
Cyfa is a play on cypher, an old English word for zero. Say it the same way: SY-fuh.
The word has travelled a long way. It starts with the Sanskrit śūnya, meaning empty, the name Indian mathematicians gave to zero. Brahmagupta set out rules for calculating with it in 628. Arabic scholars translated it as ṣifr, also meaning empty. When the Hindu-Arabic numerals spread into Europe in the Middle Ages, helped by Fibonacci's book Liber Abaci in 1202, the word came with them: cifra in medieval Latin, cifre in French, and finally cipher in English.
Europe needed it. Roman and Greek numerals had no symbol for zero, and that held back arithmetic for centuries. To people used to Roman numerals, the new digits and especially zero could be baffling, which may be how cipher came to mean a message that is hard to understand, and later a secret code. For a while it also meant any of the new digits, so writing text as numbers was, quite literally, putting it into ciphers.
English has two spellings, cipher and cypher. Cypher is the one more often seen in Britain. Cyfa is made in Kent, in England, so we went with that.
So a puzzle about making zero carries one of zero's oldest names.
The rules
- Pick 4 of the 6 numbers, each once at most, and put 3 operators between them.
- Use every operator shown that day, as often as you like, and no others. Every puzzle includes minus, because you cannot reach zero from positive numbers without it.
- Work strictly left to right. There is no "times before plus":
2 + 3 × 4is 20, not 14. - Division must come out exact. Going below zero along the way is fine.
- Reach zero only on the last step, not before.
- Find all five answers. Every puzzle has exactly five, no more and no fewer.
Two answers count as one if they are the same sum in a different order, like 9 + 3 − 8 − 4 and 9 − 4 + 3 − 8, or if one is the other with every sign flipped, like 1 − 4 − 7 + 10 and 4 − 1 + 7 − 10, which both say 1 + 10 = 4 + 7.
A worked example
Take the first one, step by step: 2 × 7 is 14, plus 6 is 20, minus 20 is 0. The third goes below zero on the way: 2 − 7 is −5, times 4 is −20, plus 20 is 0. Each answer uses all three operators, because this puzzle shows all three. This example is kept out of the daily puzzles, so it will never spoil one.
Tips for finding answers
- Work backwards from the last number. The last step is always plus or minus, so the last number has to equal the running total. Look for three numbers that make one of the others.
- Look for pairs that balance. On plus and minus days, two numbers that add up to the same as two others give an answer: 1 + 10 = 4 + 7 becomes
1 + 10 − 4 − 7. - Use the big number. The largest number is often the one you subtract at the end, so ask what makes it.
- With times or divide, think in products and multiples. For divide, only exact results are allowed, so start from numbers that share a factor.
- Watch the running total under the boxes. It shows the sum so far, worked left to right, so you can test an idea before you finish typing it.
Scoring, hints and streaks
Your score is your time. The clock starts at your first tap and stops when you find the fifth answer. It pauses when you leave the page, and you can pause it yourself with the pause button beside the time.
Stuck? A hint fills the next two boxes towards an answer you have not found, and adds 30 seconds. You get five a day. The last number is never hinted, because it is always the running total. Giving up reveals the answers you missed and ends your streak.
Your streak counts the days in a row you have found all five without giving up. Hints are allowed.
Sharing your result
When you finish, Share sends a result that shows how you did without giving anything away:
One circle for each answer, in the order you found them: yellow for an answer found on your own, blue for one a hint helped with, white for one you gave up on. The time already includes what each hint adds, and the count says how many you used, since one answer can take more than one. The same colours show on the ring around the zero in the game. After you finish, How did everyone do? shows how many players found each answer.
Questions
Is Cyfa free?
Yes. The daily puzzle is free to play in any web browser, with no download and no sign-up.
When is the next puzzle?
At midnight, your local time. Everyone gets the same puzzle on the same day. Puzzles are numbered from #1, which was 1 October 2026.
How do you say Cyfa?
Like cypher, the British way: SY-fuh (/ˈsaɪ.fə/).
Do I need an account?
No. You can play straight away. Signing in, with Google or an emailed link, keeps your progress and streak on all your devices. Nothing else changes.
Can I play past puzzles?
Not yet. For now there is one puzzle a day.
Does it work on my phone?
Yes. Cyfa is made for phones first and works in any modern browser. You can add it to your home screen to open it like an app.