This is a complete tutorial, discussing how to build a simple calculator app for Android. Check it out, and implement some of the recommended improvements.

[Click on image for larger view.] Uno Calculator (source: Uno Platform). Enabling the same C# and XAML code to run on Web, mobile and desktop is "what we do," the team said in a June 25 blog post ...

However, it is very difficult to develop a calculator that can display accurate answers, and as an example, engineer Chad Nauseam explains how the 'Calculator' app installed on Android was developed.

It uses cutting-edge machine learning technologies to create a neural network that can generate code automatically when it’s fed with screenshots of a GUI.

The Windows Calculator is now open source, and the folks at Uno Platform took the source code and put it onto Android.