Mental math · Number puzzles
Play with numbers.
A calm little arcade of mental-math games and number puzzles. No sign-up, no clutter — just you and the numbers.
Everything runs in your browser. Your best scores are saved on your device — nothing is uploaded.
Sprint
Fast mental math
Quick, timed games that get your arithmetic reflexes firing. A short run against the clock, one high score to beat.
Mental Math Sprint
A QuietCalcs originalSolve as many problems as you can in 60 seconds. Pick your operations and difficulty.
Play SprintChain
A QuietCalcs originalSolve problems back to back — one wrong answer ends the run. How long can your streak get?
Play SprintMake 24
China, card-table classicUse four numbers and +−×÷ to hit exactly 24. A tiny puzzle, endless variety.
Play SprintNumber Bonds
Classroom classicFind pairs that sum to the target — fast pattern recognition meets arithmetic.
Play SprintDigit Dash
A QuietCalcs originalBuild the biggest (or smallest) number fast — place value under pressure.
PlayPuzzles
Number puzzles, daily
The good stuff for a quiet coffee break. A fresh puzzle every day, plus an endless supply on demand.
Sudoku
USA & Japan, 1979The classic 9×9. Three difficulties, pencil marks, mistake-checking and clean keyboard play.
Play PuzzleKenKen
Japan, 2004Sudoku meets arithmetic. Fill the grid so every cage hits its target with the right operation.
Play PuzzleKiller Sudoku
Japan, 1990sSudoku driven by dotted cages and their sums. For the confident solver.
Play PuzzleFutoshiki
Japan, 2001A Latin square with greater-than clues. Pure logic — no repeats, every sign satisfied.
Play PuzzleSkyscrapers
Logic-puzzle classicA Latin square read from the edges — place 1–N so every sight-line clue matches.
PlayPuzzles
Picture and pattern logic
Grids that turn into pictures, a minefield you can clear by reasoning alone, number crosswords and the three-rule binary puzzle.
Nonogram
Japan, 1987Use the number clues to paint the grid and reveal a hidden picture. Also known as Picross and Griddlers.
Play PuzzleNewMinesweeper
USA, 1990The classic minefield, with boards you can always clear by logic. No 50/50 guesses.
Play PuzzleKakuro
USA, 1950sA number crossword. Fill each run with 1–9 so it hits its sum, with no repeats.
Play PuzzleBinairo
Belgium, 2009A binary logic puzzle. Fill with 0s and 1s — balanced lines, never three in a row.
PlaySprint
Number sense in a flash
One-tap games about the feel of numbers: where a value sits, which way it goes, what comes next.
Pinpoint
A QuietCalcs originalA number appears — tap where it lands on the line. The closer you get, the more you score.
Play SprintFlick
A QuietCalcs originalA number and a target appear. Swipe the number higher or lower before the timer runs out. One slip ends the run.
Play SprintFreeze
A QuietCalcs originalA number reel spins fast. Tap to stop it dead on the target — the closer you land, the more you score.
Play SprintEstimation
A QuietCalcs originalPick the correct answer before you can work it out exactly. Trains number sense.
Play SprintNumber Sequence
Aptitude-test classicSpot the pattern and fill in the next number. From easy runs to fiendish jumps.
PlayPuzzles
Classic brain teasers
Famous puzzles with long histories, from the 1880 sliding-tile craze to a tower that, legend says, will end the world.
15 Puzzle
USA, 1880Slide the numbered tiles back into order. The famous 1880 puzzle craze, in 3×3, 4×4 and 5×5.
Play PuzzleNewTower of Hanoi
France, 1883Move the whole stack to the last peg, one disc at a time. Can you do it in the shortest 2n − 1 moves?
Play PuzzleNewBulls & Cows
Pencil-and-paper classicCrack a secret 4-digit code from bulls and cows. The pencil-and-paper original of Mastermind.
Play PuzzleMagic Square
China, ancientArrange the numbers so every row, column and diagonal shares one magic total.
PlaySprint
Focus and memory
Hold numbers in your head and find them fast. Short drills for attention, working memory and quick sight.
Schulte Table
Germany, 20th centuryFind the numbers 1 to 25 in order as fast as you can. A classic focus and visual-search drill.
Play SprintFlash Anzan
Japan, soroban traditionNumbers flash by one at a time — add them all in your head. The classic soroban drill.
Play SprintBlink
A QuietCalcs originalA cluster of dots flashes for a heartbeat, then vanishes. How many did you see?
PlayTrain
Sharpen the basics
Short, focused drills that build the fundamentals — then track it all in one place.
Number Pyramid
Germany, school classicEvery brick is the sum of the two below it. Fill the gaps with quick adding and subtracting.
Play TrainTimes Tables
Babylon & China, ancientMaster multiplication with a fast, friendly drill you can tune from the 5s up to the 20 times table.
Play TrainPercentages
Rome, ancientTips, discounts, VAT and markups — get fast and confident with everyday percentages.
Play BadgesAchievements
Collect badges as you play. Track milestones, unlock rare achievements, and show your brain training mastery.
View badges StatsMy Number Score
One combined score across every game, tracked on your device. See where you shine and what to train next.
View your scoreWhy QuietCalcs?
Most puzzle and brain-game sites are a wall of blinking ads and pop-ups. QuietCalcs is the opposite: a clean, fast, distraction-free place to play with numbers. Every game runs entirely in your browser, works on your phone or laptop, and never asks you to sign up or hand over your data. Your scores, streaks and best times are saved on your own device.
The games are built around one idea — that a few minutes of mental math or a good number puzzle is a genuinely nice way to wake your brain up. Whether you want to get quicker at arithmetic, keep your logic sharp, or just unwind with a daily Sudoku, there's something here for a coffee break.
Alongside the number games you'll find the great classic logic puzzles, each with its rules, strategy and history: nonograms, Minesweeper with no-guess boards, the 15 Puzzle, the Tower of Hanoi and Bulls and Cows, the pencil-and-paper original of Mastermind.
The Science-Backed Benefits
Regular mental math practice isn't just fun — it builds real cognitive skills:
- Working memory — Hold multiple numbers in mind while calculating
- Processing speed — Recognize patterns and retrieve facts faster
- Cognitive flexibility — Switch between operations and problem types
- Focus under pressure — Stay calm when the clock is ticking
Learn more about brain training benefits
Make It a Habit
Consistency beats intensity. Five minutes daily builds more skill than an hour once a week. The Daily Challenge gives you one fresh puzzle every 24 hours — complete it to build your streak and watch your progress compound over time.
Frequently asked questions
Is QuietCalcs free?
Yes. Every game and puzzle is completely free, with no sign-up, no download and no ads. If you'd like to help keep it running, you can support it with a coffee.
Do I need an account to save my scores?
No. Your best scores, streaks and progress are stored locally in your browser, on your own device. Nothing you play is uploaded to a server.
Does it work on mobile?
Yes. Every game is designed to work with touch on phones and tablets as well as with a keyboard and mouse on a computer.
What's the difference between the Sprint, Puzzles and Train sections?
Sprint games are fast and timed, to build arithmetic speed. Puzzles are slower, logic-based number puzzles like Sudoku and KenKen. Train games are short, focused drills for the fundamentals such as times tables and percentages.
How do daily challenges and streaks work?
Each day features a rotating puzzle at moderate difficulty. Play at least one game before midnight (your local time) to extend your streak. Miss a day and the counter resets, but you can start fresh immediately. All tracking happens locally on your device.
Can mental math practice actually improve my brain function?
Yes. Research shows that regular engagement with mentally demanding tasks like arithmetic sprints and logic puzzles can improve working memory, processing speed, and cognitive flexibility. The key is consistent, varied practice over weeks and months.