Number memory test

How it works

Each number is shown for one second plus half a second per digit (half as long again in relaxed mode), then hidden. Type what you saw and press Enter. Spaces, dots and dashes are ignored, so you can group the digits as you type. A correct answer adds a digit; a wrong one ends the run and shows which digits slipped. Your score is the longest number you got right.

How many digits can people hold?

In 1956 psychologist George Miller described a span of about seven items, plus or minus two, for immediate memory, and digit span tasks like this one are still used in psychology. Later work, including Nelson Cowan's 2001 review, puts the underlying limit nearer four chunks, with people reaching seven or more by grouping. So group: read the number in pairs or threes (482 917 rather than 4, 8, 2, 9, 1, 7), say it under your breath, or link a group to a year or price you know.

This is a game rather than a clinical test: tiredness, distraction and practice all move your score.

Sources: Miller GA. The magical number seven, plus or minus two. Psychological Review 1956;63(2):81–97. doi:10.1037/h0043158. Cowan N. The magical number 4 in short-term memory. Behavioral and Brain Sciences 2001;24(1):87–114. doi:10.1017/S0140525X01003922