What this game measures
Digit span is the longest string of digits a person can repeat back right after hearing or seeing it. Cognitive psychologists have used this simple task for a long time as a rough window into short-term, or "working," memory. This page turns the same idea into a game. You start with 3 digits, each correct answer adds one digit, and the first mistake ends the run. The longest length you completed is your result for that run.
Your best score is kept only while this page stays open. Nothing is saved to your device or sent anywhere, a refresh clears it, and it does not sync between devices. If you want to compare runs, jot them down yourself.
Please read this: the result is not a medical or psychological assessment. Clinical versions of the task follow a strict procedure: digits are read aloud at a steady pace, there are several trials per length, and a trained examiner scores them. This page flashes all the digits at once and ends on a single error. Tiredness, noise, a distracting notification or a bad night's sleep can swing the outcome a lot. If you are worried about your memory, talk to a doctor or another qualified professional rather than relying on a browser game.
How to play
- Press Start. A string of digits appears for a few seconds, then is replaced by question marks.
- Type the digits you remember and press Submit (or Enter). Spaces and any non-digit characters you type are ignored when your answer is checked.
- A correct answer moves you up by one digit after a short pause. A wrong answer ends the run and shows the correct sequence.
- Tick the reverse box before starting if you want the backward version. Then you must type the digits in the opposite order. If the screen shows 4 8 1 9, the right answer is 9184.
The "7 plus or minus 2" idea, and its limits
In 1956 the psychologist George Miller published a paper, often summarized as "the magical number seven, plus or minus two," that is generally described as arguing that people can hold roughly five to nine items in short-term memory at once. The same paper is also known for stressing that grouping items into "chunks" lets you hold more information in the same space. Later researchers, including Nelson Cowan in 2001, argued that once chunking is controlled for, the true capacity is closer to about four items. So "7 plus or minus 2" is best treated as a rough rule of thumb, not a fixed fact about you.
What does that mean for this game? Your score depends on age, alertness, the strategy you use and even how the digits happen to fall. A single result is a snapshot of one moment, not a stable trait. This page also shows all the digits at the same time on a screen, which is a different setup from reading them aloud one by one, so there is no honest "average score" to compare yourself against. The most useful comparison is your own runs on different days.
Display time by level, and why guessing fails
The digits stay visible for 1 second plus half a second per digit. The total time grows with each level, but the time available per digit actually shrinks as sequences get longer. Each digit is drawn at random from 0 to 9 (a leading zero is possible, and repeats are possible), so a sequence of n digits has 10 to the power n possibilities. The table below is generated from those formulas when the page is built.
| Digits | Shown for (s) | Per digit (s) | Possible sequences |
|---|---|---|---|
| 3 | 2.5 | 0.83 | 1,000 |
| 4 | 3.0 | 0.75 | 10,000 |
| 5 | 3.5 | 0.70 | 100,000 |
| 6 | 4.0 | 0.67 | 1,000,000 |
| 7 | 4.5 | 0.64 | 10,000,000 |
| 8 | 5.0 | 0.63 | 100,000,000 |
| 9 | 5.5 | 0.61 | 1,000,000,000 |
| 10 | 6.0 | 0.60 | 10,000,000,000 |
| 11 | 6.5 | 0.59 | 100,000,000,000 |
| 12 | 7.0 | 0.58 | 1,000,000,000,000 |
A 4-digit sequence has 10,000 possibilities, so a blind guess succeeds one time in 10,000. At 7 digits it is one in 10,000,000. If you get a long sequence right, it is memory, not luck.
Example 1: how one run unfolds
Suppose you clear 3, 4, 5, 6 and 7 digits and miss at 8 digits. Your result for that run is 7 digits. Across the six rounds you played, the digits were on screen for 22.5 seconds in total (2.5 s for the 3-digit round up to 5.0 s for the 8-digit round). That figure excludes the time you spend typing. If you miss on the very first 3-digit round, the game simply tells you that you did not clear 3 digits.
Example 2: chunking
Grouping digits means you have fewer things to hold in mind. The table counts the groups for a few common cases.
| Case | Digits | Grouping | Groups |
|---|---|---|---|
| 10-digit phone number (US style) | 10 | 555 · 019 · 2847 | 3 |
| 9 digits in groups of 3 | 9 | 123 · 456 · 789 | 3 |
| 12 digits in groups of 4 | 12 | 1234 · 5678 · 9012 | 3 |
| 16 digits in groups of 4 | 16 | four groups of four | 4 |
You already do this with phone numbers: nobody memorizes ten separate digits when three groups will do. In this game, try silently reading the screen as 2 or 3 digits at a time, as if saying a short word, instead of letting each digit stand alone. This is widely described as a more effective strategy than rote repetition, although how much it helps differs from person to person.
Example 3: forward versus backward
In the reverse mode you must flip the order before typing, which adds a mental manipulation step on top of remembering. If the screen shows 4 8 1 9, the expected answer is 9184. Backward runs are generally described as shorter than forward runs because of that extra work. If your forward best is 7 and your backward best is 5, the gap is 2 digits. That gap is only meaningful as a comparison with your own earlier runs, not as a verdict on anything.
Practical tips and caveats
- Several runs in one sitting mix practice effects with fatigue, so do not judge yourself on one attempt.
- Writing digits down or tracing them on the desk defeats the purpose of a memory game. Try it honestly and accept the result.
- The digits come from your browser's Math.random function, which is fine for a game but not meant for security. Repeated digits in a row (7 7 3) are normal, not a bug.
- Display time is fixed for each level, so slow readers are at a disadvantage. If the timer feels stressful, track only your own progress.
- A good sitting is quiet, with notifications off. Even a short interruption can ruin a run.
Putting your result to use
Treat your score as a number that only has meaning inside this game. If it climbs after some practice, the most likely explanation is that you got better at grouping and rehearsing, which is a real, learnable skill. In daily life the same habits help: break a long number into groups, reduce how much information you take in at once, and sleep enough, because tired people struggle to hold things in mind. For a different kind of challenge, try the color sequence memory game, the memory match game, or measure your speed with the reaction time test.
Frequently Asked Questions
How many seconds are the digits shown for?
One second plus half a second per digit. A 3-digit sequence is shown for 2.5 seconds, 7 digits for 4.5 seconds and 12 digits for 7 seconds. The table above lists every level.
Does this accurately measure intelligence or memory?
No. It is a simple game and not a diagnostic test. A real evaluation of cognitive ability uses standardized procedures run by a qualified professional.
How many digits is a good score?
There is no trustworthy benchmark for this particular format, where all digits appear on screen at once. Miller's "7 plus or minus 2" is a rough research summary and depends on chunking and context, so watch how your own runs change over time instead.
Can a sequence start with zero?
Yes. Each digit is chosen independently from 0 to 9. When you answer, type the zero too. If you saw 0482, enter all four digits.
Is my score saved?
No. The best-this-visit figure lives in the open page only. Closing or refreshing it clears everything, and nothing is shared with other devices.
More memory and reaction games
- Color sequence memory game - repeat a growing pattern of colors
- Memory match game - find the matching pairs
- Reaction time test - measure how fast you respond