# calculator DUO — Scientific, history & memory

> Modern calculator with visual history, unit conversion, and pre-tax tip calculation. (iPhone/iPad app by Wenbin lei.)

- Source: https://appshunter.io/ios/app/calculator-duo/id6739860116 (this page in markdown: same URL + `.md`)
- Developer: [Wenbin lei](https://appshunter.io/developer/1787331500)
- Category: Utilities, Education
- Price: Free with in-app purchases
- Rating: 5.00/5 from 2 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 16.5 · 9 MB
- Languages: American English, Arabic, Bangla, Bulgarian, Croatian, Czech, Danish, Dutch, Estonian, Filipino and 40 more
- Released: 2025-12-08
- Data updated: 2026-09-23
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/calculator-duo/id6739860116/reviews.md

## What is calculator DUO?

A scientific calculator with history that fits the way you hold your iPhone. Save an answer, use it again in a tap, and keep everyday math moving on iPhone and iPad.

WITHIN THUMB REACH
Move and resize the left- or right-hand keypad to suit your grip.

KEEP THE ANSWERS YOU NEED
Save useful results on a visual shelf. Tap to reuse them, recall your last answer, or search your calculation history and mark favorites.

CORRECT INPUT WITH CONFIDENCE
Swipe to delete a digit or function. The deleted content stays visible until your next input; tap the return button to undo the deletion.

FROM EVERYDAY TO SCIENTIFIC
Use arithmetic, percentages, powers, roots, logarithms and trigonometric functions. Long-press a result for a large display, with adjustable text, color, font and size.

MAKE IT YOURS
Five themes, optional digit grouping and an interface in 50 languages. No account is required. Expressions, saved results and calculation history are stored on your device.

The free app may show banner ads. Remove Ads is an optional one-time purchase, with purchase restoration through the same Apple Account.

## Key features

- Visual history calculator (RESULT SHELF™)
- Unit converter
- Tip calculator (pre-tax)
- Distraction-free design
- Precise and efficient

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Remove Ads | $7.99 | one-time |


## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/calculator-duo/id6739860116/reviews.md

### 5/5 — The best calculator

*2025-12-16*

Fantastic calculator with a beautiful UI and smart features. I really like how it shows the previous result (“Before”) and the current result clearly—makes longer calculations much easier. The quick formatting (million/thousand) and the simplified number view are super convenient. Smooth performance and very well designed.

## Frequently asked questions about calculator DUO

### What makes Falculator's calculator different?

Falculator replaces traditional memory buttons with a visual history area called RESULT SHELF™, making it easier to track and recall previous calculations without memorization.

### How does the tip calculator in Falculator work?

The tip calculator in Falculator allows you to base tips on the pre-tax amount of your bill, ensuring you only tip on the cost of your food and drinks, not the taxes.

### Does Falculator have ads?

Yes, Falculator contains advertisements. It is a free app with optional in-app purchases.

### What devices is Falculator available on?

Falculator is currently supported on iPhone devices.

### How often is Falculator updated?

The latest version, 1.4, was released on January 4, 2026, indicating recent development activity. Updates are important for adding new features and ensuring stability.

### What is the age rating for Falculator?

Falculator has an age rating of 4+, making it suitable for a wide range of users.

### Can I convert units with Falculator?

Yes, Falculator includes a unit converter, described as the best available, to help you convert between various units of measurement.

### What do users like about Falculator?

Based on its 5.0-star rating from 2 reviews, users likely appreciate its intuitive design, the innovative RESULT SHELF™ feature, and its precise calculations.

## Version history (last 5 releases)

### 1.10 — 2026-09-21

• Now available in 50 interface languages, with an in-app language picker and improved regional number formatting.
• Better right-to-left layouts and large-text support.
• A compact Last button matches your saved-result cards and takes up less space.

### 1.9 — 2026-09-19

• A new name: calculator DUO. Your history, saved results, settings and purchases stay with you.
• Swipe deletions now remain visible until your next input. Tap the return button to restore the deleted content.
• The Last Answer label now has room to display fully.

### 1.8 — 2026-09-08

• Reusing a result from history now reliably starts a fresh calculation.
• Improved repeated equals, negative cube roots, percentages, and very small numbers.
• Number-format changes now update the current display immediately.
• Refined one-hand controls and full-screen result editing on smaller screens.

Your history, favorites, saved results, settings, and purchases are preserved.

### 1.7 — 2026-08-26

• Added fast search across your calculation history
• Added persistent favorites, plus pinned and filtered history views
• Refined swipe-to-delete with a red strike-through and reliable delayed removal
• Delete-button removal now stays immediate, including when combined with swipe deletion
• Smoothed expression resizing and history interactions

Your history, favorites, saved results, settings, and purchases remain on device through the update.

### 1.6 — 2026-08-23

• Long-press any result for a clean, full-screen Big Display; tap to customize its text, color, font, and size
• Expanded the interface to 21 languages
• Added an obvious X so the quick tour can be dismissed immediately
• Improved saved-result cards and long-expression trailing-edge visibility
• Refined one-hand controls, date display, and swipe-delete feedback

Your calculation history, saved results, settings, and purchases remain on device through the update.

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## More apps by Wenbin lei

- [Unit Converter: Daily Units](https://appshunter.io/ios/app/unit-converter-daily-units/id6797329964)
- [Gratuity Lab: Tip Calculator](https://appshunter.io/ios/app/gratuity-lab-tip-calculator/id6797330328)
- [Sudoku: Diamond](https://appshunter.io/ios/app/sudoku-diamond/id6797330383)

All apps by Wenbin lei: https://appshunter.io/developer/1787331500

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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 2026-09-23.*