11x13 vs Mental Math

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/

Mental arithmetic that feels like a game. An exercise sits on a chip in the middle — 7 + 5, 9 × 8 + 4, √144. Drag it onto the right answer on the board before the clock runs out. Land it and your combo grows, taking the multiplier up to ×3. Miss and you only lose the combo: nothing here breaks. HOW IT PLAYS • 14 seconds per exercise, shown by the ring around the chip: green, then amber, then red • Answer early and score more — the bonus follows those exact colours • Three correct answers in a row lift the multiplier one step • Eight exercises per chapter, up to three stars — fewer misses, more stars • No exercise repeats inside a run TWELVE CHAPTERS 1. Adding to 20 2. Adding to 50 3. Missing addends 4. Subtraction 5. Missing subtrahends 6. Times tables 7. Division 8. Square numbers 9. Square roots 10. Big numbers 11. Order of operations 12. Everything mixed FOR PARENTS • No ads, no purchases, no accounts, no sign-up • No cross-app tracking, no advertising ID — only anonymous statistics and crash reports, so we can find bugs • Works fully offline — the app needs no internet and asks for no permissions • Progress stays on the device and never leaves it Made for primary and lower secondary school, for anyone getting their mental arithmetic back up to speed — and everyone in between.