What you do in The Brain Cruncher
Start with a number. Then the steps arrive one card at a time: add, take away, multiply or divide (and in the harder chains, double, halve or square). Each card burns down like a fuse and drops into the total, which only ever shows a question mark. Keep the running total in your head and type the final answer at the end.
- Classic has four levels, from Low (5 seconds a step) to Extreme (2.5 seconds a step), with 10 steps a chain (12 on Extreme) and 3 tries at the answer.
- Memory Climb starts with 3 steps and adds one every time you crack a chain, up to 25. One miss ends the climb.
- Chain Replay shows the total after every step, and after a miss it points to the step where the chain most likely slipped.
- Low, Medium and High are free (Medium opens after 3 cracked Low chains, High after 5 cracked Medium chains). Extreme, the Fast climb and Custom practice come with Pro.
Try it: 10 seconds
No pressure. Just see how it feels.
6, then + 3, then × 2 = ?
Show the answer
18
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Doc explains
Imagine juggling one ball that changes its number every few seconds! You can't put it down and you can't peek, you just keep catching the newest version. Scientists call this updating. I can't promise it gives you a bigger memory for everything else (the research doesn't back that up), but I can promise a splendid puzzle.
The science idea
Working memory updating: keeping one piece of information in mind and swapping it for a new version every time something changes.
Psychologists describe updating as one of three core "executive" control skills, alongside inhibition (stopping an automatic action) and shifting (switching between tasks). A study of 137 college students found that the three are related but clearly separate skills.1
Doing sums in your head leans on working memory too. A review of mental arithmetic research concluded that even single-digit sums draw on its central "executive" part, and that sums with several digits are likely to involve every part of the system.2
What the research found
In that study of 137 college students, a popular working memory task called operation span leaned mostly on updating, more than on the other two skills.1
The review of mental arithmetic research concluded that working memory is involved in doing sums in your head. Its authors describe it as neither comprehensive nor systematic, so read it as a careful summary rather than the final word.2
A meta-analysis that pooled 110 studies found a medium-sized link between working memory and math (a correlation of .35), strongest for word problems and whole-number calculation.3 A correlation means the two go together; it does not show that one causes the other.
What about training working memory itself? A meta-analysis of 87 publications found short-lived gains on memory tasks similar to the ones practised, but no convincing gains on "far" skills such as reasoning, reading or arithmetic when compared with an active control group.4
How The Brain Cruncher uses it
- Every step replaces the total you are holding, and the capsule only shows "?", so you have to update the number in your head: the kind of updating psychologists study.1
- The steps mix adding, taking away, multiplying and dividing with numbers of more than one digit, the kind of mental arithmetic the review links to working memory.2
- Memory Climb grows by one step only after you crack the chain before, so the load goes up in small, fair steps.
- Chain Replay shows the running total after every step, so you can see where a chain went wrong, not only that it did.
What this does and doesn’t mean
It does mean
- Holding a changing total in your head puts updating, a well-studied working memory skill, to work.
- Working memory and math skill go together, and sums in your head draw on working memory.
- Practising the Brain Cruncher is a good way to get better at the Brain Cruncher.
It doesn’t mean
- It does not mean the Brain Cruncher gives you a bigger working memory for everything else: training gains tend to stay with the trained task or very similar ones.4
- The link between working memory and math comes from correlations; it does not show that practising a memory game raises math scores.3
- The study that separated updating from the other skills tested college students, not children.1
- The studies below tested their own tasks with their own volunteers. They did not test Math Workout.
References
Written in APA 7 style. Tap a number in the text to jump here, and the arrow to jump back.
- 1
Miyake, A., Friedman, N. P., Emerson, M. J., Witzki, A. H., Howerter, A., & Wager, T. D. (2000). The unity and diversity of executive functions and their contributions to complex "frontal lobe" tasks: A latent variable analysis. Cognitive Psychology, 41(1), 49-100. https://doi.org/10.1006/cogp.1999.0734
- 2
DeStefano, D., & LeFevre, J.-A. (2004). The role of working memory in mental arithmetic. European Journal of Cognitive Psychology, 16(3), 353-386. https://doi.org/10.1080/09541440244000328
- 3
Peng, P., Namkung, J., Barnes, M., & Sun, C. (2016). A meta-analysis of mathematics and working memory: Moderating effects of working memory domain, type of mathematics skill, and sample characteristics. Journal of Educational Psychology, 108(4), 455-473. https://doi.org/10.1037/edu0000079
- 4
Melby-Lervåg, M., Redick, T. S., & Hulme, C. (2016). Working memory training does not improve performance on measures of intelligence or other measures of "far transfer": Evidence from a meta-analytic review. Perspectives on Psychological Science, 11(4), 512-534. https://doi.org/10.1177/1745691616635612 Free to read
Science last checked: 2026-11-05
