Number Memory Practice
Recall a briefly displayed digit string forwards or backwards after it disappears. Forward314 expects314; backward314 expects413. A displayed string never begins with zero, but a reversed answer can. Use the on-screen number pad or optionally enable keyboard input. Each correct answer adds one digit, up to20. This game provides no age norms, population rankings or diagnoses.
Key features
- Start with 1–20 digits and choose 500–10,000 ms of requested exposure
- Unbiased browser random selection with no leading zero
- Forward/backward recall with displayed, expected and entered strings
- One-digit progression, exact string comparison and a 20-digit stopping point
- On-screen number pad with optional device-keyboard input
- Cancellation and hidden-tab or delayed-frame invalidation without a scored attempt
How to use
- Choose forward or backward recall, a starting length from1 to20, and an exposure duration.
- Start and observe the number. The input is unavailable while the digits are visible.
- After the number disappears, enter it with the on-screen pad. Forward keeps its order; backward starts from the last digit. Optionally enable keyboard input.
- After a correct answer, start the next level when ready. One extra digit is added. A wrong answer ends this run, and a correct 20-digit answer completes it.
- Review the round history or restart to clear it. Cancel or switch away from the tab to discard an unfinished challenge.
Use cases
- Try a short digit-recall game during a break
- Compare your own runs under the same settings
- Practice noticing and grouping digit sequences
- Learn how exposure time and sequence length change a recall task
Frequently asked questions
Does this measure intelligence or diagnose memory problems?
No. This is an unstandardized browser game. It reports only your submitted rounds and longest correctly reproduced number in the current run. It does not produce clinical memory-span values, IQ scores, age norms, percentiles or a diagnosis.
Can a number start with zero?
A displayed number starts with1–9 and later digits can be0–9. A reversed answer may start with zero: displayed100 expects001, and shortening it to1 is incorrect. Digits may repeat. Answers are compared as strings without numeric conversion.
What input is accepted?
Enter 1–20 ASCII digits. Spaces or line breaks around the answer are trimmed, but internal spaces, signs, decimal points, scientific notation and full-width digits are rejected. Incorrectly formatted input lets you try again without recording an attempt; a valid but incorrect answer ends the run. Use the on-screen0–9, delete-last and clear buttons without opening a mobile keyboard, or optionally enable keyboard input.
How does progression and the example work?
Every correct answer adds one digit to the next challenge. Start each level explicitly, and stop after a successful 20-digit challenge. The example always shows 314 for a requested 3,000 ms, is clearly labeled and runs as a demonstration. Restart before beginning a normal run after that example. The example expects314 forward or413 backward. Changing direction clears prior records, so modes are not mixed.
Is the display duration exact?
No. A monotonic browser clock and animation-frame callbacks control the viewing window, but rendering, display refresh and device load affect what you see. History shows the clock interval until the hide callback, not a measured physical screen exposure. If the hide callback is more than 250 ms late, the unfinished challenge is discarded.
What happens if I leave the tab or cancel?
Hiding the tab during observation or answer entry cancels the unfinished challenge and clears its hidden number without counting an answer. Manual cancellation does the same. Earlier completed rounds remain visible until you restart. Refreshing, changing settings or leaving the page clears the run; nothing is saved automatically.
Privacy
The settings, typed answers and round history stay in the current page’s memory. This tool does not send them to a server or tool analytics events and does not save them automatically. Restarting, changing settings or leaving the page clears the run.
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