A chalkboard sum puzzle that opens like a book: the target on one page, tiles on the other
Does Chalk & Sum work on iPhone Duo?
Yes, from launch day, and seen in a recording from the iPhone Duo simulator: open, the target sits on one page and the tiles and operators on the other.
- Simulator verifiedKartik Kaushik, the developer, in a submission to FoldHunt on October 23, 2026, and in a post on X the same day with a recording from the iPhone Duo simulator. The App Store seller is Kartik Kaushik. Chalk & Sum came out on October 23, 2026, and its App Store description says it opens like a book on iPhone Duo, the target on one page and play on the other.
Adapted for the fold
- Open · Inner display
Opens like a book
Open, the chalkboard with the target and your doodles fills one page, and the tiles, operators and Submit sit on the other, with the fold kept clear.
- Closed · Outer display
One board, closed
Closed, the target, the magnet tiles and the operators stack on the cover, with the menu buttons in the bar down the side.
About Chalk & Sum
Chalk & Sum is a number puzzle by Kartik Kaushik, drawn on a chalkboard. Each level gives a target and a row of magnet tiles: swap the tiles and place plus, minus, times and divide between them until the sum comes out right, then find every other way to make it. There’s a puzzle a day, an endless Relax mode, gentle hints in three steps, and chalk doodles to collect and arrange on your own board. There are no timers or lives. It’s free.
On iPhone Duo the board opens like a book: the target and your doodles on one page, the tiles and controls on the other, with nothing on the fold. Closed, the whole puzzle stacks on the cover. Kartik’s launch video, recorded in the simulator, shows both.
Evidence reviews
What we checked, when, and what the evidence establishes. Each record preserves the support label at that check.
· Simulator recording reviewed
Simulator verified · iphone-duo
Watched the 30-second video in Kartik Kaushik's post, captures in a flat Duo frame with the 9:41 status ring between captions: the cover with level 23, the target 24, four tiles, the operators and Submit, then the daily puzzle, the Relax map and the doodle board; open and sideways, the target and doodles on the left page and the tiles, operators and Submit on the right.
Poses shown: Closed, Open. These are observations of the evidence, not a test of every interaction.
App version: 1.0. Environment: iPhone Duo simulator.
An edited promotional video with no app or Xcode version; the half-folded pose isn't shown. No build was tested.
View reviewed evidence ↗
On X
Chalk & Sum is out now on iPhone 🎉 Swap magnet tiles, add + − × ÷, and make the number in chalk. Fill your board with doodles. No timers. No lives. No rush. Free. apple.co/4yCBSXA #iOSDev #SwiftUI #IndieDev #GameDev #Apple #duo #iPhoneDuo
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Is this your game?
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Sources: Chalk & Sum on the App Store (apps.apple.com) · Kartik Kaushik on X, announcing Chalk & Sum (x.com)
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