# Dúo Calculator — Scientific, units and history

> Scientific, units and history (iPhone/iPad app by Alejandro Hernandez Mitre.)

- Source: https://appshunter.io/ios/app/duo-calculator/id6754038433 (this page in markdown: same URL + `.md`)
- Developer: [Alejandro Hernandez Mitre](https://appshunter.io/developer/1827109770)
- Category: Utilities, Productivity
- Price: $1.99
- Age rating: 4+
- Requires: iOS 26.0 · 3 MB
- Languages: American English, Mexican Spanish
- Released: 2025-10-23
- Data updated: 2026-10-28

## What is Dúo Calculator?

Now compatible with iPhone Duo. LiquidCalculator is now Dúo Calculator: fold your iPhone Duo and it's a basic calculator; unfold it and it becomes a full scientific calculator.

On any iPhone: a basic or scientific keypad, a unit converter and your calculation history, with a precise math engine. No ads, no account and no in-app purchases.

ONE CALCULATOR, TWO SCREENS
• Folded: a basic calculator with big keys. In landscape, a compact scientific keypad appears (you can turn it off in Settings).
• Unfolded: a 10 × 5 scientific keypad with every function in view; with the screen flat, also programmer mode and a unit converter.
• Half open like a laptop, the result sits above the fold and the keypad below it. Open like a book, the keypad splits across both sides of the fold.
• Fold or unfold in the middle of a calculation and your work stays put: keys slide to their new places and the new ones appear.
• It also adapts to Split View on the inner display.

ON YOUR IPHONE
• Pick Basic or Scientific from the menu, in portrait or landscape.
• Unit converter and History on every model.
• iPhone SE and accessibility text sizes keep the big basic keys.

HISTORY
• Your last 50 calculations, newest first
• Tap a result to use it again; swipe to delete one, or clear them all
• On an unfolded iPhone Duo it opens in a panel that never crosses the fold

A REAL SCIENTIFIC CALCULATOR
• Trigonometry in degrees or radians, inverse and hyperbolic functions
• ln, log10, log2 and logarithms in any base
• Powers, roots of any degree, factorial, 1/x, π, e and EE notation
• Parentheses, memory (mc, m+, m−, mr) and the 2nd key
• Live result as you type, plus cursor editing: tap the expression to fix any point
It does not include graphing, matrices or statistics.

EXACT UNDER THE HOOD
Basic operations use exact fractions: 0.1 + 0.2 gives 0.3 and 1 ÷ 3 × 3 gives 1. Functions such as sin, ln or e^x are computed with 60 digits of precision and the display shows up to 16. Invalid operations, such as dividing by zero or tan 90°, show a clear error instead of a wrong answer. The engine is checked against an independent reference model on hundreds of test cases.

PROGRAMMER MODE (large screens, such as an unfolded iPhone Duo)
• 8, 16, 32 and 64-bit integers, signed or unsigned
• BIN, OCT, DEC and HEX at once, with a bit grid you can tap
• AND, OR, XOR, NOR, NOT, shifts, rotations, 1's and 2's complement, mod

UNIT CONVERTER
• 87 units in 11 categories: length, mass, temperature, area, volume, speed, time, data, energy, pressure and angle
• Swap units with one tap, pull in the calculator's value or send the result back to it
• Works offline; currencies are not included

YOUR WAY
• Light, dark or system theme, with optional pure OLED black
• Four accent colors: amber, indigo, mint and graphite
• Liquid Glass design; haptics and the aurora background are optional
• Copy and paste, plus hardware keyboard support
• English and Spanish, with VoiceOver labels; respects Reduce Motion, Reduce Transparency and Increase Contrast

PRIVATE BY DESIGN
• Collects no data: no account, no ads, no analytics, no tracking
• Never uses the network: the app never sends your calculations anywhere
• Settings, your last calculation and your History are stored on the device (and in its backups) and removed from it with the app

COMPATIBILITY
• Now compatible with and optimized for iPhone Duo, on both the outer and the inner display.
• Runs on any iPhone with iOS 26 or later. Programmer mode needs a large screen, such as the inner display of iPhone Duo.
• iPhone only.

Support and feedback: alex@nextechia.dev

iPhone and iPhone Duo are trademarks of Apple Inc. This app is independent and is not affiliated with Apple.

## Is Dúo Calculator safe?

Not enough ratings yet to assess Dúo Calculator.

## Is Dúo Calculator legit?

Dúo Calculator appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for Dúo Calculator is 73 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 3 releases)

### 2.0.0 — 2026-10-15

LiquidCalculator is now Dúo Calculator: compatible with and optimized for iPhone Duo.
• On iPhone Duo: folded it's a basic calculator; unfolded, a full scientific one with programmer mode and a unit converter. Half open, the result sits above the fold.
• Scientific mode on your iPhone, too: pick it from the menu or turn your phone.
• Calculation history: tap a result to use it again.
• Unit converter on every iPhone.
• New design and a high-precision math engine.
History from the previous version isn't shown in this version.

### 1.0.1 — 2026-01-05

- Navegacion por pestanas: Calculadora, Conversor, Historial y Ajustes.

- Modo cientifico con funciones avanzadas.

- Historial persistente y reutilizable.

- Mejoras visuales Liquid Glass y estabilidad general.

### 1.0 — 2025-10-23

No release notes.

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All apps by Alejandro Hernandez Mitre: https://appshunter.io/developer/1827109770

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-28.*