About Number Memory
Number Memory tests how many digits you can hold in mind at once. A number appears briefly, disappears, and you type it back. Each correct answer brings a number one digit longer, and a single mistake ends the game.
How to play
- The first round shows a one-digit number. Every correct answer moves you up to a number with one more digit.
- Numbers never start with zero, but any later digit can be anything from 0 to 9.
- The number stays visible for 1.2 seconds plus 0.45 seconds per digit, so a 5-digit number shows for about 3.5 seconds and a 10-digit number for about 5.7 seconds. A bar under it shows the time left.
- Once it disappears, type the number and submit it. There is no time limit for typing.
- Your answer must match exactly. One wrong or missing digit ends the game, and the end screen shows the number next to what you typed.
- Your score is the length of the longest number you recalled correctly.
Controls
- Keyboard: type the digits and press Enter. The answer box is focused automatically when the number disappears.
- Mouse: click Submit after typing.
- Touch: the box opens a numeric keypad on most phones; tap Submit when done.
Tips and strategy
- Chunk the number. Reading 7 4 1 9 0 6 as "741" and "906" turns six items into two, which is far easier to hold.
- Say the digits silently in a steady rhythm while the number is on screen, then keep repeating them until you type. This rehearsal keeps them from fading.
- Do not start typing the moment the number vanishes if you are still rehearsing; there is no clock on the answer, so finish your mental repeat first.
- Look for patterns such as repeated digits, runs like 3 4 5, or familiar numbers like years. Any meaning you attach helps recall.
- For long numbers, spend the display time on the end of the number once you are sure of the start, since the last digits tend to be the ones that slip.
Background
This game is a version of the digit span task, one of the oldest measures of short-term memory and a standard part of many cognitive assessments. In 1956 the psychologist George Miller published a well-known paper describing a typical span of about seven items, plus or minus two. Later research suggested that the true capacity is closer to four meaningful chunks, and that people reach longer spans by grouping digits together. That is why chunking is the most useful strategy here.
Questions
- Is there a time limit for typing my answer?
- No. Only the display of the number is timed. You can take as long as you like to type and submit.
- What counts as my score?
- The number of digits in the longest number you got right. Failing on a 9-digit number gives a score of 8.
- Does the display time increase with longer numbers?
- Yes. Each extra digit adds 0.45 seconds to the 1.2 second base time.