Take your time
Zen mode has no timer. Every wrong answer shows the method behind the correction, so you understand before the next question.
Mental math
Numvolt
mental math trainer for iPhone
Coming to the App Store
A closer lookRelease pending · Availability may vary by country
Numvolt
In the app
Real screens of the version in preparation, in French and English. The ladder screens use fictional test players and rankings, not real users or results.
Illustrative screens. Features and appearance may vary by version.
Preview unavailable. Please try again.
Take your time
Sprint against the clock
Duel on one iPhone
What you can do
Numvolt: mental math trainer for iPhone
Open, calculate, understand, repeat. Numvolt turns arithmetic practice into short sessions on your iPhone: a calm mode, timed sprints, a duel on one phone and a ladder from your city to the world.
Sprint against the clock
Choose 15, 30 or 60 seconds of addition, subtraction, multiplication and division. Your best sprint can join a ladder ranked by city, region, country and world.
Duel on one iPhone
Two players answer the same questions in turn on a single phone. Scores are revealed at the end.
In preparation. The app is in French and English. Progress stays on your iPhone: no account, no ads, nothing to buy.
At a glance
- Developer
- Roméo Gambino
- Platform
- iPhone (iOS)
- App languages
- French, English
- Price
- Free, no in-app purchases
- Account
- No account required
- Availability
- Release pending · Availability may vary by country
Guides
Further reading
How mental arithmetic works in your head, and why some methods are easier
Retrieval versus computation, where working memory runs out, why carrying is the expensive part, why anxiety costs accuracy, and what all of that means for how you practise.
A daily mental math routine that actually sticks
How long a session should be, why spacing and mixed problems beat long blocks, why being tested beats reviewing, and how to measure progress without letting the timer run the session.
Mental math techniques worth learning, and how to practise them
Left-to-right calculation, compensation, doubling and halving, shortcuts for 5, 9, 11 and 25, squares, estimation and division by chunking, with a practice method that actually sticks.
Numvolt
Questions
Is Numvolt available on the App Store?
Not yet. The app is being prepared for release; this page will show the App Store link when it is published. Availability may vary by country.
Do I need an account?
No. Progress is stored on your iPhone. Joining the ladder is optional and uses only a nickname, your city and your scores.
Where is the privacy policy?
It is published on this site: open “App privacy policy” in the footer. In short: no account, no ads, progress stored on your iPhone, optional ladder, anonymous usage counters that can be switched off in Settings.
How do I type a fraction or a decimal?
Use the / key for a fraction (3/4) and the , key for a decimal (0.75). Equivalent answers are accepted: 2/4, 1/2 and 0.5 are all correct for one half.
What does the ladder publish?
Only if you join it: your chosen nickname, your city and the region derived from it, and your best score per sprint format. It needs an iCloud account on the iPhone.
How does the duel work?
Two players answer the same calculations in turn on a single iPhone. Scores are revealed at the end.
Does Numvolt contain ads or purchases?
No. The app is free, with no in-app purchases, no ads and no account.
What does it cost?
The App Store and the app show the current price and available purchases in your local currency before confirmation. Trial availability depends on the offer and your eligibility. A free download does not mean every feature is free.
Is the app available in my language?
These are translated website pages. Check the Languages section of the App Store listing for the app itself. Some content may use a different language.
How do I manage a subscription?
On iPhone, open Settings, tap your name, then Subscriptions. Select the app to review or cancel an active subscription. Deleting the app does not cancel a subscription.
Support
Contact support
Include the app name, your iPhone model, iOS version and a description of the issue. Never include passwords or payment details.
Mental math
Numvolt
Coming to the App Store
Release pending · Availability may vary by country