Number Span

A sequence of digits appears. You read it, press a key, and it vanishes — then you type it back. Get it right and the next one is a digit longer. One mistake ends the run.

There is no timer. It runs entirely on your device: 0 network requests, works offline — no ads, no account, nothing to buy, and no betting, money or prizes of any kind.

1. Focus the board — click it, or press Tab until it is focused.
2. Read the sequence. Take as long as you like; nothing is counting.
3. Press Enter to hide it.
4. Type it back — arrow keys choose a digit, Enter enters it, Z deletes the last one. Or click the digits directly.
5. Keep going. Each round adds one digit, up to twelve.

How many digits can a person hold in working memory?

Most people land between five and nine, which is where the old "seven plus or minus two" figure came from. It is not a fixed ceiling, though: the number counts chunks, not digits. Someone who reads "1947" as one thing rather than four is using one slot instead of four, which is why practised players clear ten or eleven without their memory having changed at all.

Why is there no timer?

Because a timer would measure reading speed as much as memory, and it would make the game unplayable for anyone using a screen reader, who needs as long as the announcement takes. You decide when you have the sequence.

Why does one mistake end the run?

Because that is the stake. A task you can grind through by trial and error measures patience rather than memory, and the number it produces would not mean anything.

How do I get better at it?

Group the digits. Read "4 7 1 9 2 6" as "471" and "926" and you are holding two things instead of six. That is the whole trick, and it is the reason the score can improve without your memory improving — which is worth knowing, because the same trick works on phone numbers, OTPs and card digits.

Is there any money, betting or in-app purchase in this?

None, and there never will be. No currency, nothing to buy, no lives to refill, no wager of any kind.

Can I play it with a keyboard or a screen reader?

Both. The sequence is announced digit by digit rather than as a number — "four, seven, one", not "four hundred and seventy-one" — because the digits are what you have to remember. Every control has a key.

Starts at three digits and runs to twelve. Digits may repeat, deliberately: forbidding repeats would let you rule out possibilities and quietly flatten the difficulty curve.

If you like tasks with a hard stop, Colour Code gives you eight guesses and no more.

Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.