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Number Compare shows two values and asks which is larger, as fast as you can. It sounds too simple to be interesting until you notice the distance effect: comparing 2 and 9 is measurably faster than comparing 7 and 8, even though both are trivial. That effect is one of the foundations of modern research on number sense.
Two numbers appear side by side.
Choose the larger one immediately.
Response time is recorded for every comparison.
Correct answers load the next pair.
Pairs get closer together as you progress.
Magnitude comparison — the approximate number sense that operates below deliberate calculation. It is present in infancy and in other species, and its sharpness varies between people. Another math game to try next: Math Bingo.
Do not calculate the difference. Judge magnitude directly; calculating is far slower.
For multi-digit numbers, compare digit counts first, then leading digits.
Expect close pairs to be slower. That is the effect being measured, not a failure.
Rest your fingers over both response keys so neither side is favoured.
Comparisons get faster the further apart the two numbers are. It is a robust finding and it suggests numbers are represented on something like a mental number line rather than looked up as symbols.
The accuracy is trivial; the reaction times are not. This is a speed measure, not a correctness one.
Whole numbers, yes.
Adjacent numbers are the hardest comparison there is, for everyone. The closer the magnitudes, the more overlap in their internal representation.