Serial Addition — Free PASAT-Style Working Memory Test
Add each number to the one before it — not the total.
- Working memory
- 4 min
- Hard
Serial Addition is a browser version of the PASAT, a clinical measure of information-processing speed and working-memory updating. The rule sounds simple and is deceptively hard: you add each new number to the previous number, which means the answer you just said is immediately useless and you must discard it.
Play Serial AdditionHow it works
1Numbers arrive one at a time, at a fixed pace.
2Add each one to the PREVIOUS number — not the total.
3Then discard it. The answer you just gave is dead weight.
How to play
- 1
Numbers arrive one at a time
A new number appears at a fixed pace. Each one stays only briefly.
- 2
Add it to the PREVIOUS number
Not to your running total. If you see 3 then 5 then 2, the answers are 8 then 7.
- 3
Keep pace
The interval shortens as you level up. The moment you fall behind, the next number is already gone.
What it trains
Hold and update information while under load. Updating — swapping stale contents out of working memory for fresh ones — is one of three separable executive functions and predicts reasoning performance.
- Brain area
- Prefrontal cortex — executive updating
- Based on
- Miyake et al., 2000
Leaderboard
Weekly season resets every Monday. Scores show as Lvl 5.
Leaderboard
Questions
Why is this so much harder than it looks?
Because you have to actively discard the answer you just produced. Holding onto it is the natural instinct and it is exactly what breaks the task.
Is this the same as the clinical PASAT?
It follows the same rule and pacing structure. It is a training exercise, not a diagnostic instrument — do not read a clinical result into your score.
What level should I aim for?
Level 4 sustained is a good target. Level 6+ requires genuinely fast updating.
