Press Start, click or tap 1, then tap the numbers it hides in order: your biggest board is your score.
ReadynumbersA sample board. Press Start, then tap 1 and the rest hide.
More options
The standard run. Four numbers to start, one more after every cleared board, and the run ends on your third strike. Nothing hides until you tap 1, so study the board for as long as you like. Your score is the biggest board you cleared.
–This run
–Your best
–Last run
Starts at 4 numbers on a 6 by 6 board and adds one after every cleared board, up to 20. Nothing hides until you tap 1. Tap the squares in rising order. A wrong tap is a strike and a new board of the same size. The run ends at 3 strikes. The result is the biggest board you cleared.
Levels 4 to 6: read it in one pass. Three to five squares are hidden once you tap 1, which allows 6, 24 or 120 possible orders. The route is short enough to trace once from 1 to the end. Use these boards to fix the habit of tracing before you tap, because that habit carries the later levels.
No runs yet. Your last ten will show up here.
Today's boards
The same boards for everyone today. Finish a run and a badge counts your days in a row.
Classic climb from 4The standard run. Four numbers to start, one more after every cleared board, and the run ends on your third strike. Nothing hides until you tap 1, so study the board for as long as you like. Your score is the biggest board you cleared.
Glance climbThe climb with a limit on looking. Every board hides itself after 3 seconds, whether or not you have tapped 1, so there is no time to rehearse the route twice. It keeps its own best, apart from the classic climb, because the two are not comparable.
Head start at 7Skips boards 4, 5 and 6 and keeps the three strikes. Use it once those early boards have stopped costing you strikes: a run to level 12 takes 6 boards here against 9 from the start.
Head start at 10Opens on ten numbers, so nine squares are hidden from your very first tap. For players whose best is already in the teens and who want every board of a session to be a hard one.
Open board practiceThe numbers stay visible the whole time, and nothing is scored or saved. Use it to settle your scan: find 1, trace the route to the last number, then tap it through at an even pace. Two boards of this make a useful warm-up.
Sudden death climbThe same climb with one strike instead of three. A single wrong square ends the run, which makes this the quickest way to find the level you can clear every time and not just on a kind board.
Show all 23 rounds and techniques (17 more)
Flash rounds from the research 3
Flash round: 210 msThe condition the test is known for. Inoue and Matsuzawa reported in 2007 that the young chimpanzee Ayumu put five numerals in order about 79% of the time when they were shown for 210 ms. On a 60 Hz screen the flash lasts 13 frames, about 217 ms, and the page reports the length it measured.
Flash round: 650 msThe same five-numeral board, shown for 650 ms, about three times as long as the 210 ms flash. In a 2010 follow-up study, two students who practised first substantially outperformed the chimpanzee, so practice is the point of this round. Start here if 210 ms looks like a blank screen.
Flash round: 1,000 msOur own warm-up for the two rounds below. Five numerals drawn from 1 to 9 appear for one second, then all five turn into white squares. Tap the squares from the lowest numeral to the highest. A run is 10 boards, and the score is how many you got fully right.
Level by level 5
Levels 4 to 6: read it in one passThree to five squares are hidden once you tap 1, which allows 6, 24 or 120 possible orders. The route is short enough to trace once from 1 to the end. Use these boards to fix the habit of tracing before you tap, because that habit carries the later levels.
Levels 7 to 9: split the route in twoSix to eight hidden squares, and 40,320 possible orders at level 9, so guessing is over. Trace the first four numbers as one shape and the rest as a second, then run both once more before you tap 1.
Levels 10 to 12: three legsNine to eleven hidden squares, and a third of the 36 cells numbered at level 12. From level 10 at least two numbered cells must touch, corners included, because a 6 by 6 grid has room for only 9 that do not. Break the route into three legs of three or four numbers.
Levels 13 to 16: fix each leg to the frameTwelve to fifteen hidden squares, and at level 16 four cells in every nine carry a number. Numbers that sit side by side are the ones that get swapped, so note which row each leg starts on and which edge it ends at.
Levels 17 to 20: learn the gapsAt level 18 half the grid is numbered, and at level 20, where the climb stops, only 16 cells are empty. It can be easier to remember the shape of the empty cells round a leg than the leg itself. Clearing level 20 ends the run with a full score.
Techniques 9
Anchor to edges and cornersOnce the numbers hide, the only landmarks left are the frame and the white squares. Store 7 as bottom row, second from the right, and not as just under 6, because a neighbour is no help when it has turned into a white square too.
Keep your hand off the boardOn a phone, a tapping hand covers part of the grid. Hold the phone in one hand and tap with a finger of the other, coming in from below the grid, so the squares you have not reached yet stay in view.
Name each leg of the routeNine numbers is a long list, but three shapes is a short one. Trace 1 to 3, pause, 4 to 6, pause, 7 to 9, and name each leg as you go: hook, stairs, corner. When the squares turn white you replay three words.
Play short sessionsA classic run to level 12 is at least nine boards of full concentration. Play three to five runs, note the best, and come back tomorrow. The chart of your last ten runs shows whether the practice is working.
Read the reveal after a strikeAfter a wrong tap the page shows every number again before it deals a new board. Two neighbours swapped means you need firmer anchors. A blank from some number onwards means your legs were too long: drop from four numbers a leg to three.
Run the last leg once moreYou trace the end of the route last and tap it last, so it waits longer than any other part. Before you touch 1, run the final three numbers again. If your strikes keep landing on the last few squares, this is the fix.
Study before you tap 1In the climbing rounds nothing hides and no clock runs until you tap 1. The score is the level you reach, not the time you take, so a board studied for 20 seconds counts exactly the same as one studied for 2.
Tap at the pace you tracedPlay the route back at the speed you rehearsed it. Stopping halfway to think breaks the gesture and leaves you hunting square by square. If you do lose the thread, restart the current leg in your head from its first number, not from 1.
Trace the route, not the placesFollow 1, 2, 3 and onwards with your eyes as one continuous line until it feels like a gesture. A route that runs top left, top right, bottom left, bottom right is the letter Z, and a Z is one thing to remember where four cells are four.
How this list was compiled: Rounds, level notes and techniques written for this page. The counts were computed on 2026-09-19: the possible orders of n hidden squares are n factorial (3 squares 6, 4 squares 24, 5 squares 120, 8 squares 40,320); the shares of the 36-cell grid are 12 of 36 (a third), 16 of 36 (four in nine) and 18 of 36 (half); a 6 by 6 grid splits into nine 2 by 2 blocks, so 10 numbered cells must put two in one block, where they touch; a run to level 12 takes 9 boards from level 4 and 6 from level 7; and a 210 ms flash on a 60 Hz screen (one frame every 16.7 ms) rounds to 13 frames, about 217 ms. The research facts were checked on 2026-09-19. Inoue S, Matsuzawa T, 'Working memory of numerals in chimpanzees', Current Biology 17(23): R1004-R1005, December 2007, https://doi.org/10.1016/j.cub.2007.10.027. The figure of about 79% for five numerals between 1 and 9 shown for 210 ms and masked with white squares, and the point that Ayumu had many practice sessions while the human subjects had none, are from the abstract of Silberberg A, Kearns D, Animal Cognition 12(2): 405-407, 2009, https://doi.org/10.1007/s10071-008-0206-8, which also reports two practised humans matching his accuracy. Cook P, Wilson M, Psychonomic Bulletin and Review 17(4): 599-600, 2010, https://doi.org/10.3758/PBR.17.4.599, reports two students who outperformed the chimpanzee after practice and finds no evidence of a superior spatial memory system in chimpanzees. The open question about boards of seven or more numerals is as given at https://en.wikipedia.org/wiki/Cognitive_tradeoff_hypothesis, re-read on 2026-09-19. That article also gives the 2010 students a 650 ms training flash and scores of 94% and 96% at 210 ms, in a sentence with no footnote; the abstract does not give those figures, so the page leaves them out. The 650 ms round is simply a longer flash: 650 divided by 210 is 3.1. Ayumu's birth on 24 April 2000 and his mother Ai are from https://en.wikipedia.org/wiki/Ayumu_(chimpanzee). The citation of the 2007 paper and the abstracts of the 2009 and 2010 papers were read from their PubMed records (PMID 18054758, 19115068 and 20702883). Licence: own work
How it works
The chimp test scatters numbers over a 6 by 6 grid. Tap 1 and the rest turn into white squares, which you tap in order from memory. Clear a board and the next one has one more number, up to 20. Three strikes end the run. Your score is the biggest board you cleared.
Read the full guide
How the squares hide
Press Start and four numbers appear. Nothing hides until you click or tap 1, so trace the route first. A wrong square is a strike: the board shows where everything was, then deals a fresh one at the same level. On a keyboard, arrow keys move and Enter or Space taps a square. Under Round, Sudden death climb allows one strike, Head start at 7 skips the early boards, and Open board practice never hides anything.
Where the chimp test comes from
The chimp memory test is named after a 2007 report by Inoue and Matsuzawa in Current Biology. A young chimpanzee, Ayumu, put five numerals in order about 79% of the time when they flashed for 210 ms. No student tested came close, though he had many practice sessions and they had none. Flash round: 210 ms recreates that condition: five numerals, one blink, ten boards.
Name each leg of the route as you trace it: hook, stairs, Z. At level 9 you replay three words, not eight positions.
A 60 Hz screen draws a frame every 16.7 ms, so a 210 ms flash is 13 frames, about 217 ms.
Strikes landing on the last few squares? Run the final three numbers again before you tap 1.
Questions and answers
What is a good score on the chimp test?
The one published yardstick is Ayumu's: about 79% on the 210 ms flash task. That is roughly 8 boards in 10 on Flash round: 210 ms, after long practice on a laboratory touchscreen. This page has no measured average for the climbing rounds, so beat your own best in the same round on the same device.
Are chimpanzees really better at this than people?
Once people practised too, the gap closed. In 2009 two practised people matched Ayumu's accuracy. In a 2010 study two students who practised first substantially outperformed him, and its authors found no evidence of a superior memory system in chimpanzees. Boards of seven or more numerals are still an open question.
Should a low chimp test score worry me?
No. The score moves with practice, route planning, tiredness, screen size and whether you use a mouse or a finger, and it says nothing about intelligence or health. If your memory worries you in daily life, talk to a doctor.