Number Memory Test
A number flashes up, then vanishes. Type it back. Each one is a digit longer, until they slip.
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Bar widths show roughly how many people land in each band on the provisional curve. Your number is the longest one you typed back right. A number shows for up to one second a digit (hide it early once you have it); a miss gets you a second number of the same length, a second miss ends the run.
What moves it
Chunking. Nobody holds twelve digits; they hold four groups of three. Read a number the way you read a phone number and the groups do the carrying.
Saying it. Digits stay as sound more than as a picture. Say them under your breath while the number shows and keep the rhythm going until you have typed them.
Sleep and attention. Working memory is the first thing a short night takes. A slip at five digits on a tired day is not a smaller memory, it is a lapse; the second try at each length is there for exactly that.
What this measures
Digit span is the classic measure of short-term memory, in use since the 1880s and still in every clinical battery: see a number, hold it, give it back. Its famous result is how narrow the human range is. Most adults hold about seven digits, give or take two, and raw intelligence barely moves that; what moves it is strategy, chunking digits into groups, which this test quietly measures on top of capacity.
A number shows for one second per digit, then vanishes; type it back and the next one is a digit longer. A miss deals a second number of the same length, and a second miss at that length ends the run, which is exactly how the clinical form stops. Only the length is scored: you can hide the number early once you have it, and take as long as you like to answer.
The starting curve is Human Benchmark's published histogram of saved scores, shifted down one digit because saved scores select for the proud, standing in until this site's own runs outweigh it; the Method page carries the live count. Why seven and not twelve, and what grouping does about it, is the subject of the memory guide.
Questions people ask
It is the longest number you typed back right, in digits. Numbers start at three digits and grow by one each time you get one right. A miss gets you a second number of the same length; miss that too and the run is over. Nothing else is scored: how long you take to answer is on the card, but it does not move the number. Hiding the number early changes nothing but how long you looked.
Because a lapse is not a limit. One glance away at five digits should not hand a five to someone who holds nine, and one miss and out makes the score mostly luck near your limit. The clinical digit-span test gives two numbers at each length and stops when both are missed; this test borrows that stopping rule. The second number is a fresh draw, so the first try gives nothing away.
Seven, give or take two, is the figure everyone quotes for short-term memory; the provisional curve here sits one digit above it, re-centered on Human Benchmark's saved scores and shifted down one for self-selection: 8 is the middle, 10 is a long number, 13 is rare. Every digit shows for one second, all at once (less if you hide the number early), and you can take as long as you like to answer, so expect to land a little above what a spoken digit-span test would give you. The curve is an assumption until humanlag has its own runs.
Nothing stops you, and nothing can: a pen, a screenshot, a friend reading the screen. Typing while the number shows is refused, and pasting into the answer is refused, but the test measures what you hold, and only you know whether you held it. The score is yours to keep honest.
No. A browser test measures a day of your life, not your brain's architecture: sleep, stress, interruptions and how seriously you took the run all land in the number, and the normal range is wide. The clinical version is administered aloud by a professional under controlled conditions, and even there a single low result means little on its own. If your memory worries you, that conversation belongs with a professional, not with a percentile.
It starts as an assumption worth 1000 runs, shaped from published norms, and every run played here adds one to it, everyone in one pool. The Method page says which norms, how the percentile is read, and how many runs this test has measured so far.