Calculator XplusY

Objective:

The goal was to build Calculator XplusY for crea:do — a calculator for Android and iOS where the formulas people use every day sit on their own buttons, so a repeated calculation takes one tap instead of a string of operations.

Creative Process:

The whole app rests on a simple logic: X is the number you enter before pressing a formula button, and Y is the number you enter after it. A discount, a markup or VAT becomes a single button — type the price, tap, type the percentage.

We built the app in Flutter, so Android and iOS share one codebase and behave the same. Users write their own formulas, assign them to buttons and reorder those buttons into a layout that fits how they work. Core calculations run offline; only currency conversion goes online to fetch current exchange rates.

Results:

Calculator XplusY launched in September 2025 on the App Store and is also available on Google Play.

• Custom formulas: Users create and save their own formulas and place them on buttons they can reorder freely.
• Predefined library: Ready-to-use calculations for finance, engineering, physics, geodesy, unit conversions and electromobility.
• Two calculation modes: Instant evaluation or step-by-step results, with the formula displayed during the calculation.
• Currency conversion: Up-to-date exchange rates, while the core calculations work without a connection.
• History and themes: A log of previous results, dark and light mode, and custom button colors and backgrounds.

What We've Done:

• UI / UX Design Implementation
• Multiplatform Flutter App Development
• QA & Testing

Tech Stack:

• Flutter

Conclusion:

Calculator XplusY shows that even a tool as familiar as a calculator has room for a better idea. A single Flutter codebase brought that idea to both platforms at once.