What number comes next? 2, 4, 8, 16, …
Doubling is one of the first rules most people check, which is what makes this a good early item. The interesting part is what happens in the two seconds before you commit to it.
Pattern recognition and working memory
Each number doubles the one before it, so the sequence continues 32, 64, 128. The trap answer is 24, which comes from noticing that the gaps are growing and adding the last gap again instead of testing whether the rule is multiplicative.
Number series items measure two things at once. First, whether you generate more than one candidate rule instead of committing to the first one that fits. Second, whether you can hold the earlier terms in working memory while you test a rule against them.
Working memory is the small workspace where you keep information you are actively using. George Miller put its capacity at roughly seven items in 1956, and later research suggests the real figure is closer to four. It is the bottleneck in most reasoning tasks.
How to get better at spotting patterns
Nobody is born knowing to test multiplication once addition has failed. It is a checklist, and a checklist is something you can learn in an afternoon and keep for good.
The reliable improvement here is procedural rather than biological. People who are good at these do not have larger working memory, they have a habit: check addition, then check multiplication, then check the differences between the differences, before answering.
That habit transfers to real problems. The equivalent at work is generating a second explanation before acting on the first one, which is the single most useful thinking habit on this list and the one most people skip when they are in a hurry.
- Always test at least two candidate rules before committing
- Write the differences between terms down instead of holding them in your head
- Check your rule against every term, not only the last two
- Notice when growth is accelerating, which usually signals multiplication
Writing things down instead of juggling them is not cheating, it is the correct response to a small working memory. The same principle drives most of the advice in our guide to study tips that actually stick, which opens in a new tab.
Next up is verbal reasoning, where the material changes but the underlying job stays similar.