11x13
Mental math up to calculus
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Train mental math — from basic operations to derivatives and integrals. The basic operations are free forever.
A short problem, nine answers, one correct — 11x13 trains mental math with no clutter and no words in the problems.
THE BASIC OPERATIONS ARE FREE. NOW AND FOREVER.
Addition, subtraction, multiplication and division with level bands that grow with you: from small times tables over carrying to the 11–19 tables — the app's namesake — plus chained problems like 47 + 8 + 6 at high levels.
WITH “EVERYTHING” YOU PRACTICE EVERY OPERATION.
Unlock every package permanently with a one-time purchase or for the duration of a subscription. The 14-day app trial ends automatically without starting a subscription:
• Percentages: from 50% of round numbers to surcharge and discount
• Roots: squares and cube roots
• Powers: up to powers of two and ten
• Derivatives and integrals: from monomials to binomials
• Geometry: symbol equations (▲ + ▲ = 12), counting corners, matching shapes
• Fractions: adding like fractions, simplifying, unlike denominators, multiplying
Your progress grows per operation, syncs via iCloud, with progress charts and a Game Center leaderboard.
Easy to keep at it: a daily practice reminder at the time you choose, a Home Screen widget with the problem of the day, and statistics with streak, week-over-week comparison and band history.
With a true iPad layout and hardware keyboard support (keys 1–9).
Subscriptions renew automatically until cancelled in App Store subscriptions. A one-time purchase provides permanent access.
Mistake notebook: The last 100 tasks you answered incorrectly are saved on this device. Review up to ten tasks without time pressure. A task leaves the notebook after a correct first answer in two separate rounds.
EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
New: a mistake notebook and untimed review rounds. Each attempted task now counts once, even with several answer attempts. Previous statistics are preserved.
New: buy permanent access to Everything or subscribe. Existing permanent purchases remain valid. Purchase options, restore and subscription management are available together.
The developer, Matthias Hennemeyer, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Matthias Hennemeyer
- Size
- 2.9 MB
- Category
- Education
- Compatibility
Requires iOS 15.6 or later.
- iPhone
Requires iOS 15.6 or later. - iPad
Requires iPadOS 15.6 or later. - iPod touch
Requires iOS 15.6 or later. - Mac
Requires macOS 12.5 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 6 more
- English, French, German, Italian, Japanese, Simplified Chinese, Spanish
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Everything – monthly $0.99
- Everything $5.99
- Copyright
- © 2026 Matthias Hennemeyer
