June 15, 2026
No rounding, no chill
A calculator that doesn't round
iPhone gets a calculator that never fudges the numbers, and the comments are losing it
TLDR: A developer made an iPhone calculator that keeps answers exact instead of rounding them, even for ridiculous math tricks. Commenters were fascinated by the AI-built backstory, joked about token costs, and debated whether Apple’s own calculator already does a watered-down version.
The big flex here is wonderfully nerdy: an iPhone calculator that doesn’t round off your answers and will keep spitting out more correct digits as long as you keep scrolling. That means weird math party tricks like Ramanujan’s constant looking exactly like a whole number for ages before finally wobbling, and giant-number nonsense like adding 42 to a monstrously huge value and still getting exactly 42 when you subtract it back out. The creator jumped into the comments to say they built it by porting the same exact-math engine used by Android’s calculator, with one artificial intelligence model helping do the translation and another catching bugs.
And yes, the comments instantly turned into a mix of awe, nitpicking, and comedy. One person cut straight to the modern question of the year: how many tokens did this AI-assisted coding adventure burn through? Another skipped the app entirely and pitched the next escalation: why stop at a calculator when we could have a full symbolic math wizard on a phone? Then came the sneaky plot twist from the crowd: someone claimed the built-in iPhone calculator can already show Ramanujan’s constant in scientific mode — but only up to the famous run of 9s, basically turning the thread into a tiny courtroom over whether this app is a breakthrough or a glorious overachiever.
The funniest vibe in the room is that people are equal parts impressed and delighted by the absurdity. A calculator app about not rounding sounds niche, but the community treated it like a crossover episode between old-school math fandom, App Store tinkering, and AI coding drama.
Key Points
- •The article describes an iPhone app, Constructive Calculator, that uses constructive real arithmetic to produce exact results without rounding and lets users scroll for more digits.
- •It contrasts the app’s behavior with IEEE 754 floating-point arithmetic, using examples such as `exp(100) + 42 − exp(100)` returning exactly 42 instead of 0.
- •The app was built by porting Hans Boehm’s Java constructive-reals library and Android ExactCalculator components, including `com.hp.creals`, `UnifiedReal`, and `BoundedRational`, into Swift.
- •The implementation used Opus 4.8 for line-by-line translation into Swift, while the author handled architecture, UI, testing, and App Store workflow.
- •A clean-room review by Fable 5 found multiple issues introduced during adaptation to Swift concurrency, including incorrect main-actor isolation, a cache race with memory-safety implications, and a UI freeze from synchronous factorial evaluation.