Number Memory
A number appears for a few seconds, you type it back, and it grows by one digit each round until you miss. Your longest correct number against a normal curve with mean 7.5 and SD 1.6.
A number appears for a few seconds. Type it back. Each round adds one digit. One mistake ends the test, and your score is the longest number you got right.
Play until you miss one to see your digit span.
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About this test
Number memory shows a number for a few seconds, hides it, and asks you to type it back. Each round adds a digit until you make a mistake; the score is the longest string you got right. Miller's 1956 paper put adult digit span at seven plus or minus two, and Human Benchmark's user data agree with a median around 7 to 8. The module uses a normal curve with mean 7.5 and SD 1.6.
Span is about chunking, not raw capacity. Cowan (2001) argues that working memory holds about four chunks; people reach seven digits by grouping them into pairs or triples, which is why phone numbers are written 555-0123 and not 5550123. Memory athletes reach 100 digits and more by turning digit groups into images.
What is a normal digit span?
Seven digits, give or take two, for adults (Miller 1956). Scores of 9 or more are above the 80th percentile on our curve; 5 or fewer is below the 10th. Fatigue and distraction cost a digit or two.
Why is the score lower than I expected?
Reading digits off a screen under time pressure is harder than hearing a number read aloud, and a single wrong digit ends the run. Many people also rush the typing; the time limit is on viewing, not on typing.
Can I train number memory?
Yes. Chunking into groups of two or three is worth a digit or two immediately. The major system, which maps digits to consonant sounds and then to words, is how memory competitors reach spans in the hundreds.
Percentiles above come from the same parameters the Number Memory module uses. See the methodology for how they are calculated.