Sumflash: Mental Math Flash

Numbers appear on screen one at a time, each for just a moment. Add them all up in your head and enter the total. This is flash mental math, the way it's practiced with the soroban (Japanese abacus). There are 30 levels, and you practice at the one you choose.

- See why you missed After each answer, review every number that flashed along with the running total at that point. Numbers where a carry happened are highlighted, so you can spot exactly where you slipped. Replay the same problem, or replay it slowly.

- From 0.2 to 5.0 seconds Set the speed yourself anywhere from 0.2 to 5.0 seconds per number.

- 30 levels From 1 digit, 3 numbers, 1 second each, each level changes one thing at a time: more numbers, then faster, then more digits (up to 3 digits, 15 numbers, 0.5 seconds). Change your level anytime from the home screen. Already experienced? Pick a higher starting point on the first launch.

- A daily habit Your home screen shows your streak: how many days in a row you've practiced. Miss just one day in a Monday-to-Sunday week and your streak stays alive. One set is five problems and takes just a few minutes. Set a daily reminder at a time you choose (it stays quiet on days you've already practiced).

- Five themes • Minimal: thin numbers on white • Washi: Mincho numerals and a red seal • Neon: glowing numbers • Chalkboard: chalk numbers on green • Sakura: rounded numbers on pale pink Your records carry over when you change themes.

- For the whole family Each profile keeps its own level, practice days, and records.

- Ranked play and leaderboards One digit, ten numbers, a little faster each stage. Your fastest cleared display time goes to Game Center leaderboards (today, this week, all time; global and friends).

- Add, subtract, multiply, divide Pick one from the tabs on the home screen. Addition and subtraction (mixed plus and minus) flash numbers one at a time; multiplication and division flash a single expression like "23 × 7". Each has its own 30 levels to choose from.

- Read aloud Have numbers read aloud as they flash.

- Also • An optional tick sound with each number (plays even in Silent mode; you can turn it off in Settings) • Numbers simply appear and disappear, with no animation getting in the way • Records are stored only on your device (if you're signed in to Game Center, only your best ranked-play time is sent to Apple for the leaderboard) • No sign-in

- Premium (auto-renewable subscription) • No ads Monthly subscription. The price is shown in the app and may vary by region. It renews automatically every month and is charged to your Apple ID unless you cancel at least 24 hours before the renewal date. Cancel anytime in iPhone Settings › Apple ID › Subscriptions. Premium only removes ads. Every other feature is free.

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