Number memory test tips, for digit strings and for Hidden Numbers
· 5 min read · Tyamka team
How grouping and naming positions help you remember numbers on a grid, how the timer and lives work, and why your score jumps between attempts.
The most useful tip for remembering more digits is to group them, ideally in threes. Below is how that works with a string of digits, and how to carry it over to Hidden Numbers, our number memory test online. In that game numbers appear on tiles, you tap 1, the rest hide, and you tap the hidden tiles in order from the smallest up. It is not the classic test where you repeat a string of digits, so some familiar advice fits and some does not. There is also a section on how the game counts, and why the same person can score 80 one minute and 130 the next.
Group digits in threes
In digit span research, grouping is the best known way to hold more. In 1964 Wayne Wickelgren asked people to repeat strings of 6 to 10 digits and told them to rehearse the digits silently in groups of different sizes. Groups of three worked best, better than twos and clearly better than fives, with fours close behind threes. You already do something like this with a phone number when you read it in parts. If a group looks like something you know, a year or a house number, take it as one piece.
Know what the game is asking
Two details of the rules make the job smaller than it looks.
- You only need the order. When the numbers hide, their tiles stay visible as filled squares, and the empty tiles cannot be tapped. So you never have to remember which tiles had numbers. You only need to remember which of the visible tiles comes first, second, third.
- A mistake shows you the answer. A wrong tap costs one of your three lives, and the game outlines the tile you should have tapped. You keep your points, and the level goes on from the same number. You lose the level only when all three lives are gone.
How the timer works
The points for a level are 10 for every correct tap plus a speed bonus of up to 10. The bonus shrinks by one point for roughly every 300 milliseconds between one correct tap and the next. Where the clock starts depends on the level.
- Levels 1 to 5. The numbers stay on screen until your first correct tap, and the clock runs from the moment they appear. So the time you spend memorising counts against your bonus on the first tap. Looking a little longer costs a few bonus points, while a wrong tap costs a life. On these levels a longer look is usually the cheaper choice.
- Levels 6 to 15. The numbers hide by themselves, after 2 seconds on level 6, 1 second on level 10 and 430 milliseconds on level 15. Here the clock starts when they hide, so the show time is not counted against you. Tapping 1 while the numbers are still visible hides the rest at once. That tap gets the full speed bonus, but you lose the rest of the only look you get. Waiting keeps the whole show, and a quick first tap after the hide can still earn the full bonus.
Use threes on the grid
Wickelgren's study was about digit strings, not positions on a grid, so what follows is our suggestion, not something measured in the game. Instead of trying to see seven separate tiles, look at 1, 2 and 3 as one shape, then 4, 5 and 6 as a second shape, then whatever is left. Three tiles almost always make a recognisable shape, such as a line, a corner, a triangle or a zigzag. When you tap, you replay shapes instead of single tiles.
On the later levels, nine numbers make three shapes of three, and eight make two shapes of three and a pair. With less time, you may find it easier to look for the first shape first and not try to see the whole grid at once.
Name the path to yourself
Another suggestion, also untested in our game. Give the path short names in your head, like "top left, down, across" or "corner, middle, corner". Saying something to yourself is a second way of holding it, next to the picture of the grid. It is easier to try on the early levels where the numbers stay up until you tap, because naming takes time. On the fastest levels there is only time to see the shapes.
Why your score jumps between attempts
If you play the same level five times, you will likely get five different scores. Several things move it.
- The layout is new every time. Each attempt places the numbers on a new random set of tiles. Sometimes 1, 2 and 3 sit in a neat row, sometimes they are scattered across the grid, and the second kind is harder to hold.
- The bonus is sensitive to pauses. One hesitation of a second or so before a tap can take several bonus points off that tap. A level with seven numbers has a maximum of 140 points, and pauses alone can take a large part of it.
- Mistakes add up. A wrong tap costs no points directly, but you lose time while you find the right tile, and that shows up in the bonus.
- The day matters. Sleep, noise and how rushed you feel can all show up in a short game like this.
So one good or bad attempt tells you little. Three attempts on the same level, and the middle score of the three, tell you more.
Practice changes the numbers
In the study this game is based on, published by Sana Inoue and Tetsuro Matsuzawa in 2007, untrained university students did poorly when five numbers were shown for only 210 milliseconds. Later work by Alan Silberberg and David Kearns (2009) and by Peter Cook and Margaret Wilson (2010) found that people who practised the task did much better. Practice on a task like this helps with that task. We do not claim that it improves memory outside the game.
For what research says about the usual range of number memory, read the article on the number memory test average. For the idea behind all these games, read what working memory is. Other games are on the all games page.