Four Nines
Play the classic four 9s puzzle as a free daily math game: three targets a day, four copies of one digit, one calculator. Fewest symbols wins. No sign up.
Free to play in your browser — no download, no sign up.
A daily puzzle for a calculator with one number key. Three targets a day. Four copies of one digit each. Hit the number exactly, in as few symbols as you can.
How to play
- Three puzzles a day. Easy, medium, and hard. Each one deals four copies of a single digit from 1 to 9 and a target number. Nines are the house canon; the calendar picks the rest.
- One number key. Use exactly four copies of the digit. Stick them together (99) or put a point in front (.9); both still count toward the four.
- Every other key. Combine them with + − × ÷, powers (^), modulo (%), factorials (!), square roots (√), and parentheses. Order of operations counts.
- Exact, then short. Hit the target exactly. Any answer solves it; a shorter one scores better.
How scoring works
Every operator you press costs one symbol: + − × ÷ ^ % ! √. So does every decimal point. Parentheses are free, and so are the four digits.
Par is the fewest symbols the solver needed for that puzzle. Your result reads like golf: at par, or +2 if you took two more. Under par does not happen: if you beat the solver, par moves to you.
Solve any of the day's puzzles on its own day to extend your streak. Past days wait in the archive; solve them whenever, they just don't count toward the streak.
Stuck? Each puzzle has three hints: how many operators par uses, one of those operators, then the shape of the answer.
Example solutions
(9 + 9) / (9 + 9) = 1— A balanced fraction turns four identical numbers into one.9 / 9 + 9 / 9 = 2— Two simple fractions make a tiny target.(99 - 9) / 9 = 10— Concatenating two 9s opens up larger intermediate values.99 + 9 / 9 = 100— The most famous four nines solution of them all.
Stuck on a number? The Four Nines solver has verified solutions for every target from 1 to 100 — for example, making 100 with four 9s.
The classic four nines problem
The four nines problem — also known as the four 9s puzzle — is a classic of recreational math: take exactly four 9s and write an expression for a given number. It has been set as a classroom challenge for over a century, and it works because it sits in the sweet spot between mental math and logic puzzle. You can brute force small targets, but better solutions come from recognizing useful building blocks: 9 / 9 for 1, 9 + 9 for 18, 99 for larger jumps, and parentheses for changing the order of operations. Four Nines turns the classic into a daily game: three targets a day, each with four copies of one digit — nines when the calendar cooperates — and a symbol count that rewards the tidy answer over the first one.
FAQ
What is the four nines problem?
It is a classic math puzzle, also called the four 9s puzzle: using exactly four 9s and arithmetic operations, write an expression that equals a given number. For example, (9 + 9) / (9 + 9) = 1 and 99 + 9 / 9 = 100. Four Nines turns the classic problem into a daily game: three new targets every day, each with four copies of one digit — the calendar picks it, nines are the canon.
How do you play Four Nines?
Each day has three puzzles: easy, medium, and hard. Each gives you a digit and a target number. Combine exactly four copies of that digit with the calculator's keys — + − × ÷, powers, modulo, factorials, square roots, and parentheses — to build an expression that equals the target. Order of operations counts.
How does scoring work?
Each operator and each decimal point costs one symbol; parentheses and the four digits are free. Par is the fewest symbols the solver needed for that puzzle, and your result reads like golf: at par, or +2. 99 + 9 / 9 = 100 costs 2 symbols, which is par.
Why is it called Four Nines if today's digit is a 7?
Nines are the canon: the classic problem this game grew from uses four 9s, and the solver and target pages here run entirely on 9s. The daily deals four copies of one digit from 1 to 9 so the habit stays interesting. The name stays — it is the brand, and 'Four Sevens (Some Days)' is not a name.
Do I need advanced math?
No. It is arithmetic on a calculator keypad. Square roots, factorials, powers, and modulo are on the keys when a puzzle wants them; the challenge is in arranging things, not in knowing anything fancy.
Can there be more than one answer?
Yes. Many targets have several valid expressions, and finding a shorter or stranger solution than your first one is half the fun.
Is Four Nines free?
Yes. Four Nines is free to play in your browser on burger fun — no download, no sign up, no account.
I searched "four nines" looking for 99.99% uptime.
Wrong kind of four nines — that one is an availability target, this one is a daily math puzzle. Ours is more fun than an SLA, permits unlimited downtime, and you are welcome to stay.
The Number Lab
Same idea, different constraints: four 9s, four 4s, or any four digits you like.
- Four Nines — the daily puzzle (this page)
- Four Nines solver — every target, solved
- Four Fours — the 1881 original
- Four Fours solver — including the impossible five
- Make 24 solver — any four digits
- Today's 24 — one new hand a day