Number Scanning Game
Scan a grid of numbers. How many follow the rule?
About Number Sense
Number Sense first announces a rule, for example 'How many numbers are above 50?'. Then a grid of two-digit numbers is flashed on the screen for a few seconds. When it disappears you slide to the count of numbers that follow the rule. You cannot count them all in the time you have, so you have to scan and estimate.
There are between 16 numbers on level 1 and 36 on level 10, and the display time falls from 4.5 to 2.5 seconds. The first levels use simple rules such as above or below a boundary and even or odd. From level 4 the game also asks for multiples of 5 and for numbers in a given decade, like the 40s.
How to play
- Read the rule in the question. It stays in your mind while the numbers show.
- Scan the grid in a few sweeps. Look for the numbers that follow the rule and ignore the rest.
- When the grid disappears, slide to the number of matches and lock in within 10 seconds.
- The answer note gives the total number of numbers on the grid, so you can see the proportion that matched.
Read the rule in the question, then a grid of numbers appears briefly. Slide to how many of the numbers follow the rule.
How scoring works
The score depends on the distance between your count and the real count. You get 100 for an exact count, and the score falls in a straight line to 0 at a distance of about a third of the grid on level 1 and roughly 18 percent of the grid on level 10, with a minimum of 3. For a grid of 36 numbers on level 10 an error of 3 still earns about 50 points.
The numbers are drawn at random between 10 and 99. The game makes sure that the real count is at least two, so the question is never empty. The slider runs from 0 to the size of the grid, so it contains no hint about the answer.
What it trains
The game trains rapid visual search combined with a small piece of arithmetic knowledge: knowing at a glance whether a number is even, over 50 or a multiple of five. It is about fluency with numbers, which many people find is one of the first things to fade when they do not use it.
It also trains selective attention. To count the right group, you must keep the rule active and filter out everything else while you scan.
Tips for a higher score
- Sweep the grid row by row at a fixed pace. A systematic scan beats random jumping.
- For even or odd numbers, only look at the last digit. For multiples of 5, look for 0 or 5 at the end.
- For above or below a boundary, look at the first digit. A '5' as first digit needs a second look; other digits decide immediately.
- Keep a running tally in groups of three or four instead of single steps.
- Estimate in proportions. If about half of the grid looks to match, the answer is about half the size of the grid.
The idea behind it
Searching for items that match a target in a field of distractors is a classic topic in attention research, going back to the feature integration theory of Anne Treisman and Garry Gelade in 1980. When the target is defined by a simple visual feature it stands out, but when it has to be recognized from its meaning, as with the number rules in this game, search becomes serial and takes longer.
Parity judgements (even or odd) are well studied too. The SNARC effect, found by Stanislas Dehaene and colleagues in 1993, shows that people respond faster to small numbers on the left and large numbers on the right, which suggests that we imagine numbers on a mental line.
Frequently asked questions
Is the grid really random?
Yes, every number is drawn at random between 10 and 99. The game only makes sure that at least two numbers follow the rule.
Do I have to remember the rule?
No. The rule stays at the top of the screen while the grid is shown, and the question is repeated when you give your answer.
What similar games exist?
Gut Total estimates a sum, and Odd One Out in the Focus category trains visual search.
Related games
Free, no account. Your best scores are saved on your device.