Number Peek

How does Number Peek work?

Number Peek is a number memory game with a cover over the number. You press and hold the cover to see the digits, and the moment you let go they hide again. Each round gives you one peek.

1. Round 1 hides a 3-digit number. The first digit is never zero.
2. Hold the cover with a finger, the mouse or the Space key. An amber bar drains while you look.
3. Let go, and the cover locks. Only now does the answer box open.
4. Type the number and press Check answer. A right answer makes the next number one digit longer.
5. A wrong answer gives you one retry with a new number of the same length. Two misses in a row end the run.

Your score is the longest number you got right plus your total look time, for example "6 digits, 8.3 s of looking". Looking less for the same digits is the better run.

How long can one peek last?

A peek lasts at most one second plus 0.6 seconds for every digit. When the bar runs out, the number hides as if you had let go, and the full limit counts as look time. The table is computed from the same rule the game uses.

The time per digit shrinks as numbers grow, from 933 ms at 3 digits to 667 ms at 15. Long numbers get harder even if you use the whole bar.

Worked example: scoring one run

Here is a run of seven rounds. Every peek adds to the look time, including the rounds that went wrong.

1. The miss at 6 digits in round 4 costs nothing but time. Round 5 is a retry with a new 6-digit number, and it is right.
2. Round 6 misses at 7 digits, and the retry in round 7 misses too, so the run ends.
3. The longest right answer had 6 digits. The peeks add up to 8.3 seconds.
4. The result reads 6 digits, 8.3 s of looking.

What happens in one round?

Every round runs through the same three steps. The answer box never opens while the digits are on screen.

How many digits can people hold at once?

Psychologist George Miller wrote in 1956 that people "can repeat back eight decimal digits, but only nine binary digits." In the same paper he concluded that immediate memory is limited by the number of items, not by how much information each item carries.

Miller called the items chunks, and noted that "the memory span is a fixed number of chunks." That is why Number Peek shows digits in groups of three: if you read 407 188 23 as three groups instead of eight single digits, there is less to hold. Number Peek is a game, not a medical or research test, so we show no norms or percentiles. Your chart compares you with your own runs.

Your last 10 runs

Questions