Sumhow
A calculator that fights back
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
The keys are gone. The math still works. Reach the target in the fewest presses, then learn to spell upside down.
Somebody left you a calculator. Most of the keys are gone.
Sumhow hands you a target and a handful of surviving keys, and asks you to make the number anyway. Three, plus and times are enough to get started. Then the machine starts changing the rules on you.
HOW IT PLAYS
• Every unit has a par: the fewest presses it can possibly be done in. Match it for three stars.
• The machine resolves left to right, with no order of operations. On this unit, 3 + 4 × 2 is 14.
• Undo and Clear are free, so experiment. There are no timers, no lives and no fail state.
TEN CHAPTERS, ONE RULE EACH
Roots, where √ only lands on whole numbers. Echo, where equals repeats the last operation. Decay, where the × key dies after two uses. Stutter, Memory, Wraparound, The Toll, Below Zero, Blind. And Word Mode: ninety-six trivia questions whose answers you spell by typing the number that reads as the word when the screen is upside down.
The first four chapters are free. Each of the ten that follow is a single purchase, or earn it: every unit in a chapter at three stars pays for the next one in gold.
HINTS THAT COST SOMETHING
A nudge shows your next press. A route shows the whole solution. Both cost gold and cap the stars you can earn on that unit, so a hint is a choice, not a shortcut.
SKINS
Wear the calculator you want. Forty-three skins in seven packs, from leopard print to a synthwave sunset, tried on before you buy.
THE QUIET PART
The unit reacts to certain numbers. None of them are listed. Scratch mode is a fully working calculator with no target; that is where you go looking. Find enough and a chapter opens that is not for sale.
No ads. No account. No energy meter. Just a calculator with a problem, and you.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Timothy Palladino, 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
- Timothy Palladino
- Size
- 17.1 MB
- Category
- Puzzle
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Sweet Shop skin pack $1.99
- Wild skin pack $1.99
- Seaside skin pack $1.99
- Night Shift skin pack $1.99
- 80s skin pack $1.99
- Desk skin pack $1.99
- Skins: Café $1.99
- Chapter 6: Wraparound $4.99
- Chapter 7: Word Mode $4.99
- Chapter 8: The Toll $4.99
- Copyright
- © 2026 Kismet Studio LLC
