Zen mode: understand before moving on
No timer. When an answer is wrong, Numvolt shows the method that leads to the right one, so the next question starts from something you learned.
Mental math
Numvolt
mental math trainer, times tables & arithmetic on iPhone
View on the App Store
A closer look Check the App Store for availability in your country. Checked on 16 October 2026. Final availability depends on your Apple account country.
Available on the App Store
Numvolt
In the app
Preview language : English
The ladder screens use fictional test players and rankings, not real users or results.
Screens from version 0.2.14
Illustrative screens. Features and appearance may vary by version.
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Zen mode: understand before moving onTimed rounds and a rankingTwo players on one iPhone
What you can do
Numvolt: mental math trainer, times tables & arithmetic on iPhone
Get your mental math back in shape in short sessions, from times tables to fractions, percentages and square roots. Every mistake comes with the method, and you can race the clock or a friend on the same iPhone.
Timed rounds and a ranking
Choose 15, 30 or 60 seconds. If you wish, your best score joins a ranking by city, region, country and world, under a nickname.
Two players on one iPhone
Both players answer the same calculations in turn on a single phone, and the scores are revealed at the end.
No account or ads. For new installations, Numvolt Pro is required after the welcome. A local profile that had already finished the welcome or answered a question before version 0.2.13 keeps access on that device. Pro is offered as a yearly auto-renewing subscription or a one-time lifetime purchase; the app shows the local price and any eligible trial before purchase.
At a glance
- Developer
- Roméo Gambino
- Platform
- iPhone (iOS)
- App languages
- English, French, Arabic, Bangla, Catalan, Czech, Danish, German, Greek, Spanish, Persian, Finnish, Filipino, Hebrew, Hindi, Croatian, Hungarian, Indonesian, Italian, Japanese, Kannada, Korean, Marathi, Malay, Norwegian Bokmål, Dutch, Punjabi, Polish, Portuguese, Romanian, Russian, Slovak, Slovenian, Swedish, Swahili, Tamil, Telugu, Thai, Turkish, Ukrainian, Urdu, Vietnamese, Simplified Chinese, Traditional Chinese, Gujarati, Malayalam, Odia
- Account
- No account required
- Availability
- Available on the App Store
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.
How to calculate percentages in your head, step by step
Build any percentage from 10%, 5% and 1%, swap the numbers when it helps, and handle discounts, tips, tax and percentage change without a calculator.
How to multiply two-digit numbers in your head
Four ways to multiply two-digit numbers without paper: splitting, rounding and correcting, the difference of squares and numbers near 100, with worked examples.
Mental math for interviews: what to practise and how
How to prepare for interview arithmetic in consulting, finance and trading: estimation, zeros, percentages, growth, the rule of 72 and calculating out loud.
Mental math games for adults, and how to keep them useful
Timed sprints, target-number puzzles, the 24 game, dice and card games, duels and estimation: how each format works, what it trains and how to keep it honest.
How to improve number sense as an adult
What number sense is, what research on estimation and magnitude does and does not show, and practical exercises that build a feel for numbers.
How to divide numbers in your head, with worked examples
Division as a missing multiplication, halving chains, dividing by 5, 25 and 125, chunking, estimating quotients, and turning remainders into decimals.
Times tables tricks: how to learn the multiplication table for good
How few facts you really need, tricks for the 9s, the 6s and the other hard ones, and practice methods from research that make the multiplication table stick.
Successive discounts: calculate the real reduction
Calculate 30% then 15%, work backward from the final price and check the effect of rounding.
Check equivalent fractions and decimals
Simplify a fraction, convert a finite decimal and distinguish an exact answer from a rounded approximation.
Negative numbers: check the sign before calculating
Distinguish a negative sign from subtraction, check worked integer examples and enter a signed result in Numvolt.
Unit price calculator: compare prices per kg or litre
Compare two pack sizes on the same unit basis, follow the division and check quantities, rounding and limits.
Order of operations: work through each step
Use brackets, equal-priority operations and explicit notation to check a calculation before adding speed.
Mental math practice without guessing: a better daily loop
Use mental arithmetic to practise methods, check errors and build speed without confusing a fast guess with a reliable answer.
Mental Math Multiplication Shortcuts: Multiply Numbers in Seconds
Master practical mental arithmetic techniques for fast two-digit multiplication, squaring and distributive breakdown without pen or paper.
Mental math apps, compared
Drill apps, method teachers, competitive trainers and flashcards: which one builds speed, which one builds understanding, and why the difference shows up later.
Numvolt
Questions
Is Numvolt available on the App Store?
Yes. Numvolt is on the App Store for iPhone. 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 account or ads. For new installations, Numvolt Pro is required after the welcome. A local profile that had already finished the welcome or answered a question before version 0.2.13 keeps access on that device. Pro is offered as a yearly auto-renewing subscription or a one-time lifetime purchase; the app shows the local price and any eligible trial before purchase.
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
View on the App Store
Check the App Store for availability in your country. Checked on 16 October 2026. Final availability depends on your Apple account country.
Available on the App Store