A number appears, disappears, and you type it back — each success adds a digit
Number Memory shows a number, hides it, and asks you to type it back. Each success adds a digit. It is the simplest and most widely recognised memory benchmark there is, and unlike most tests it gives you a single number you can watch move over weeks.
A number appears on screen for a few seconds.
It disappears.
Type it back exactly.
Each correct answer adds one digit.
One mistake ends the run at the length you reached.
You choose a starting length of 3 to 6 digits and a speed. The number is shown for 0.6 seconds plus 0.4 seconds per digit (longer on slow, shorter on fast). A correct answer adds one digit to the next number and one to your streak.
A wrong answer does not end the game: the next number is one digit shorter (never below your starting length) and your streak resets. Your best streak and the longest number you have recalled are saved in this browser.
Short-term memory span for digits. The raw capacity is limited and fairly stable, but chunking strategy is not — and that is where almost all the improvement comes from. Another memory game to try next: Missing Object.
Holding a string of digits is the oldest measure of short-term memory in psychology. George Miller's 1956 paper put the typical limit at about seven items; later work by Nelson Cowan argued that the true capacity of attention is closer to four chunks, and that people reach seven or more by grouping digits into chunks.
How far chunking can go was shown in 1980 when a student trained for over 230 hours and raised his digit span from about seven to 79 — not by expanding memory, but by recoding digits as running times he already knew. The gains did not carry over to letters, which is the clearest demonstration that span training builds a strategy, not a bigger memory.
Chunk into threes and fours the way you would a phone number. This is the single biggest lever.
Say the digits out loud. Spoken rehearsal holds longer than silent visual rehearsal.
Turn chunks into meaningful things — years, ages, prices. Meaning survives far longer than digits.
Type immediately. Every second of delay costs you a real chance of losing the tail.
The famous 'seven plus or minus two' comes from George Miller's 1956 paper and was about chunks, not digits. Real digit spans vary a lot with presentation speed, so track your own trend rather than a headline figure.
Chunking, and nothing else. Nobody holds twelve individual digits; they hold three or four chunks.
Materially, yes. Articulatory rehearsal is more durable than visual.
Almost. Digit Span also offers a backward mode, which asks you to reverse the sequence and is significantly harder.