Memory & Differences
This section trains short-term number memory and quick comparison. You will remember one digit, see the next digit, and type the positive difference between the two.
What this trains
This practice focuses on short-term memory, quick comparison, and staying accurate under time pressure. You will need to remember the previous digit while quickly calculating the positive difference from the next digit shown.
Instructions
- 1Choose a duration and start the test.
- 2After a 3-second countdown, the first number appears for 2 seconds. Do not answer yet.
- 3For each next number, type the positive difference from the number before it.
- 4Numbers are 1-9. Each difference is always 1-4, so only those answer keys are used.
- 5Use regular number keys, numpad keys, or the on-screen keypad (if you are using mobile).
Test rhythm
ATSA-style Memory & Differences practice is fast-paced. The goal is not only to get answers right, but to keep a steady rhythm. The next number appears shortly after each answer.
Example
The answer is the absolute difference: |2 - 5| = 3.
You only need to remember the previous digit, not the full sequence.
Practice tip
Say the first number in your head, then replace it with the new number after you answer. Do not try to remember the whole sequence — only the previous digit matters.
Practice options
Test Mode is distraction-free: no feedback, no visible score, and results only after the timer ends.
No feedback or score is shown until the timer ends.