Number Memory Test

How the number memory test works

Press start and a number appears, beginning with 3 digits. It stays on screen for about one second per digit, with a bar along the bottom counting down, and then it vanishes. Type what you remember and press Check. Get it right and the next number is one digit longer. Get it wrong and you have a second try at the same length with a new number. Miss both and the test ends.

Forwards and backwards

In forwards mode you type the number exactly as you saw it. In backwards mode you type it in reverse, so 4 8 1 becomes 1 8 4. Backwards is noticeably harder, which is the point: it measures how well you can rearrange what you are holding, not just how much you can hold.

How your score is worked out

Your score is your digit span: the longest number you typed back correctly. Two tries at each length, ending when both are missed, is the same rule used by traditional clinical digit span tests, called the two-error maximum length. That is also how the 763 adults in the study we compare you with were scored, so the comparison is fair as far as the rules go. One difference remains: they heard the digits read aloud one at a time, while here you see the whole number at once.

Saving and sharing

Your best span in each direction and your last results are kept in your browser, so you can track your progress on this device without an account. We also record each finished test, with your country but never your IP address, for our statistics; our privacy policy explains how. Challenge a friend creates a link with your score that shows them the number to beat.

What is a good number memory score?

The best yardstick comes from a 2011 study that tested 763 adults in a community sample, aged 18 to 65, with a computerised digit span test scored the same way as this one (Woods and others, 2011):

"Typical" covers the range most adults in the study reached. Only about 3% had a forward span as short as 4.

Treat a single result loosely. In the same research, people's backward spans varied by almost a digit from one testing day to another, and a lapse of attention on one number can end the test early. Two or three runs, on different days, give a much better picture than one.

How many digits can the average person remember?

About six or seven, when you repeat them straight back. The best-known answer comes from the psychologist George Miller, whose 1956 paper argued that people can hold roughly "seven, plus or minus two" items in mind at once (Miller, 1956). The study above, with a median of 6 and an average of 6.35, sits comfortably inside his range.

Later research suggests the true limit is smaller still. Reviewing a wide range of experiments, Nelson Cowan concluded that when people are prevented from rehearsing or grouping items, they hold only about four chunks (Cowan, 2001). The two findings fit together: you reach six or seven digits because you quietly repeat them to yourself and group them into pairs and triples, so seven digits may only be three or four chunks.

Digit span and working memory

Digit span is one of the oldest memory tests still in use, and for decades it has been part of the Wechsler intelligence and memory scales for adults and children (Woods and others, 2011). The two directions measure slightly different things:

• Forward span mostly measures short-term storage: how much you can keep in mind for a few seconds.
• Backward span adds manipulation: you hold the number while reversing it. That combination of holding and working on information is what psychologists call working memory.

The study found the difference shows up with age and schooling. Forward span did not change significantly between 18 and 65, while backward span dropped slightly with age. Both were a little higher in people with more years of education, with the stronger link again for backward span. The current Wechsler adult test, the WAIS-5, scores working memory with number tasks such as putting digits in order from lowest to highest; our guide to the WAIS lists them alongside the other subtests.

Why the language you count in changes your span

Part of your span depends on how quickly you can say the numbers to yourself. Researchers testing Welsh-English bilinguals found that Welsh digits take longer to pronounce, and the same people had significantly shorter digit spans in Welsh than in English (Ellis and Hennelly, 1980). They concluded that this word-length effect, not any difference in ability, explained why Welsh children scored lower on a digit span test than American children of the same age. If you think in a language with long number words, your span here may not reflect your memory as well as it would in a shorter-worded language.

Can you improve your number memory?

For numbers specifically, dramatically. In a famous experiment, a student known as SF spent more than 230 hours practising in the lab and raised his digit span from 7 to 79 digits (Ericsson, Chase and Faloon, 1980). His method was to turn groups of digits into running times he knew from his own training. His memory for other things did not grow in the same way; he had built a skill for digits. Our guide to photographic memory explains how his chunking worked and lets you try it.

That pattern is typical. Practice and strategies make you better at the exact task you train, and much less at memory in general. If your aim is a higher score on this test, chunking will get you there. If it is a sharper memory for everyday life, sleep and general habits matter more; our photographic memory test measures memory for rooms, grids, chessboards and words as well as numbers.

Tips for a better score

• Group the digits. Read 7 digits as three chunks, such as 841 93 72, rather than seven single numbers.
• Say them silently. Repeat the chunks to yourself in a steady rhythm while the number is on screen and as you start typing.
• For backwards, chunk first and reverse second. Reverse each small chunk, then type the chunks in reverse order.
• Type straight away. Short-term memory fades within seconds, so start typing as soon as the box appears.
• Test when you are fresh. Tiredness and distraction cost more than a digit. Compare your results on different days to see your real range.

Number memory is one small part of how your mind works. For reasoning rather than recall, try our free IQ test, or test your speed with the reaction time test.

Frequently asked questions

Sources

• Woods, D. L. and others (2011). Improving digit span assessment of short-term verbal memory. Journal of Clinical and Experimental Neuropsychology, 33(1), 101–111.
• Miller, G. A. (1956). The magical number seven, plus or minus two: some limits on our capacity for processing information. Psychological Review, 63(2), 81–97.
• Cowan, N. (2001). The magical number 4 in short-term memory: a reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87–114.
• Ericsson, K. A., Chase, W. G. and Faloon, S. (1980). Acquisition of a memory skill. Science, 208(4448), 1181–1182.
• Ellis, N. C. and Hennelly, R. A. (1980). A bilingual word-length effect: implications for intelligence testing and the relative ease of mental calculation in Welsh and English. British Journal of Psychology, 71(1), 43–51.