Six minutes a day, calculator back in the drawer.
Dear person who still reaches for the phone calculator at the till,
So do most adults, and there is no shame in it. But if you have searched for mental math practice for adults, you probably want the small daily version, not a textbook. Here is a 90-second test you can take right now, with an instant timer, and then an honest account of what a six-minute daily puzzle app does for this and what it does not. We make one of those apps, Cognilo; this letter is where we are allowed to say so.
Five everyday sums, timed
0.0secondsType the answer, press Enter or Check. The clock starts on your first keystroke. Numbers only; the dollar sign is assumed.
Notice what that felt like. The sums were not hard; the pace was the thing. That is the whole premise of Cognilo's Real Numbers round: everyday money and time sums, worked out in your head, at your level, with a tip afterwards about how you might have done it faster. Not a lecture on arithmetic. A rehearsal of the till.
Questions you will have
Does practising sums make me better at sums?
Yes, and that is nearly all the research supports. The 2016 Simons review in Psychological Science in the Public Interest found people tend to improve on the specific tasks they practise, with little evidence for broad transfer to other tasks. So: practise the sums you actually meet, which is what Cognilo's Real Numbers round is.
Will a brain-training app make me smarter or protect my memory?
No app on this page claims that, and Cognilo's listing says its ratings describe how you play Cognilo puzzles and are not a measure of intelligence or health. In 2016 the FTC fined Lumosity $2 million over claims like that and required competent and reliable scientific evidence for any future benefit claims.
How long is a session?
About six minutes for the Daily 5 at a typical pace, per the listing; days with the Market Run shopping scenario take a little longer, and after a few rounds the app shows your own estimate before you start.
Is it timed?
Untimed by default (Precision). Sprint adds a timer for a push; Zen is unrated. The 90-second test above is timed only so you can see your pace; in the app you choose.
Is Cognilo free?
The free tier is complete, per the listing: the Daily 5, all six skills, ratings, the Benchmark and achievements. Pro is an optional monthly or annual subscription for the Performance Lab (Pressure Response, Interference), weekly and monthly reports, and up to 12 months of rating history.
Do I need an account?
No. Local-first, no ads, no tracking; history stays on the device and exports as JSON. Purchases and optional Game Center leaderboards need a connection; competition is off by default.
What we will not claim
- No transfer promise.Practising sums improves sums. The 2016 Simons review found little evidence that brain-training gains transfer broadly; we are not going to tell you otherwise, and the app's listing says ratings are not a measure of intelligence or health.
- There is a subscription.Cognilo Pro, monthly or annual, for the Performance Lab and reports. The free tier is complete and you can tap Continue Free on the paywall.
- Ratings move slowly on purpose.Performance Ratings only move when several sessions agree, and the Benchmark uses held-out rounds. If you want a number that jumps after a good morning, this will frustrate you.
- New app.Released September 2026, iPhone and iPad on iOS 18 or newer. Few reviews yet.
How a day works
- Open it; the first puzzle starts.No sign-up, no questionnaire. Five rounds from five of six categories: memory, focus, logic, numbers, spatial, language.
- Get a result and a tip per round.Plain-language reason for why that puzzle was picked, a strategy tip, pace versus accuracy, and an unrated Review replay of anything that slipped.
- Come back tomorrow, or not.Rhythm counts days per week rather than a streak; Grace and Vacation cover busy weeks. Nothing punishes a missed day.
Who should not bother
- Anyone wanting a cognitive assessment. See a clinician. This is a puzzle app and says so.
- Children. It is a puzzle game for adults, per the listing; the sums are rent and restaurant bills, not homework.
- People who want a streak to chase. Rhythm counts days per week instead. If the streak is your fuel, pick something else.
- Android. iPhone and iPad only, iOS 18.
Yours, with the calculator still in the drawer,
Honest Little Apps
Play free on iPhone
Cognilo: Brain Training Games. Five puzzles, about six minutes, untimed by default. No account, no ads, works offline. The free tier is complete.
Sources
- Simons, D. J., et al. (2016). Do “Brain-Training” Programs Work? Psychological Science in the Public Interest. Summary: University of Illinois News Bureau (people improve on the specific tasks they practise; little evidence for broad transfer).
- Federal Trade Commission, 5 January 2016: Lumosity to Pay $2 Million to Settle FTC Deceptive Advertising Charges.
- Cognilo: Brain Training Games on the App Store, listing read 4 November 2026 (version 1.2.0): Daily 5, puzzle list, modes, ratings and Benchmark, free tier and Pro, privacy.
The five sums above are ours; the timer runs in your browser and stores nothing.