Crab Math Run
Math practice on the pier
$3.99 · Designed for iPad. Not verified for macOS.
Answer the sum in the sun and the parrot flies a plank across the gap. Right answers earn gems for the pier and the sea. One purchase. No ads. Nothing collected.
Math practice built to keep you playing.
A crab walks a pier over the sea, and the math problem rides inside the sun. Answer it and the parrot flies a plank across the gap. Answer fast and the next problem is already waiting. At the end of the run the boat comes in and presses every shell earned into gems.
The math is real, and you set it
• Addition, subtraction, multiplication and division: one sign, plus and minus, times and divide, or all four
• Three levels: numbers 0 to 4, 0 to 9, and 0 to 12
• A custom range anywhere from 0 to 20, or one number to drill, like the sevens
• Four speeds, from 15 seconds a problem down to 4
• Type the answer on a keypad, or pick from four choices
• Every fact in the range comes up once before any repeats
No shame in a wrong answer
In Safe mode, the default, a missed problem still gets its plank, with the whole fact written on it, and the hero never falls. The parrot's key stays dark, and play goes on. Splash mode is there for players who want stakes: the boards run out, the hero goes in, and the boat pulls him out with a rope ladder every time. The run ends there, but shells already earned are always paid.
Ways to play
• Timed runs of 1, 2 or 5 minutes
• Relax, with no clock: the boat comes the moment you call it
• Flash cards for pure study, with the answer on the back
• Missed: every fact you miss is kept in one list, and two right answers in a row take it off
A sea that grows with every right answer
Gems come only from right answers, and they cannot be bought. They dress the pier and the seabed: 11 things for the pier, 10 for the sand, flags for the boat, snails, and food for the fish. Thirteen kinds of sea life join your water as your gems add up. Four super creatures, the Great Orca, the Manta Ray, the Beluga and the Narwhal, patrol the deep, and each one asks a sum of its own when you tap it. A treasure chest on the sand asks one too.
Pick your hero: a crab, an octopus or a snail.
Good to know
• One purchase. No in-app purchases, no ads, no subscriptions
• No accounts, no sign-in, and nothing is collected. Progress stays on the device
• Plays without an internet connection
• Every run ends with a summary: accuracy, average answer time, longest streak, and what was earned
• The Records book keeps a page for every kind of run
Ratings & Reviews
The developer, Clay Elmore, 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
- Clay Elmore
- Size
- 24.1 MB
- Category
- Education
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 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+
- Copyright
- © 2026 Arbolinea
