How the Number Speed and Accuracy task works
Three numbers appear, each in its own box. Working in your head, you pick out the highest and the lowest. Then you decide which of those two is further away from the third number, the one in the middle, and click it.
There is no calculator and you do not need one: each item is two small subtractions and a comparison. What the task measures is how quickly and reliably you do that.
How to solve each item
Run the same three steps every time:
- Find the middle number first. Once you know it, the other two are the highest and lowest.
- Work out the gap from the middle number up to the highest, and down to the lowest.
- Click the end number with the bigger gap. Never click the middle number: it can never be the answer.
Worked example
The numbers are 14, 9 and 21. The middle number is 14. The highest, 21, is 7 above it; the lowest, 9, is 5 below it. 7 is the bigger gap, so you click 21.
Next item: 33, 18 and 27. The middle number is 27. The highest, 33, is 6 above it; the lowest, 18, is 9 below it. This time the lowest number is further away, so you click 18.
Tips for the real Number Speed and Accuracy task
- Do not look for a median or an average. The answer is always one of the two outside numbers.
- Work out both gaps by subtraction rather than by eye. Close calls, such as gaps of 6 and 7, are where errors come from.
- A wrong answer is reported to cost half a mark, so with three boxes a blind guess gains nothing on average. Guess only if you have ruled one out.
- Warm up on quick mental subtraction in the days before. This task rewards fast, sure arithmetic more than anything clever.
- Use the practice examples to settle on the middle-number-first routine before the clock matters.
Practise GIA Number Speed and Accuracy on CogniPrep
Our Number Speed and Accuracy drill gives you generated three-number items from 1 to 30 on a 2-minute clock that starts when the first item appears and never pauses, with no fixed count. Every item has exactly one right answer, and each wrong answer costs half a mark. At the end you see how many items you reached, how many were wrong, your adjusted score and a percentile against CogniPrep players. The 2-minute clock and the number range are ours, because Thomas publishes neither.