Using a few HTML statements and a little JavaScript, you can build your own calculator that performs addition. This task is not as difficult as it seems because HTML creates calculator controls ...

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.

Source code of the "my first app" tutorial for the WWC mobile community, featuring the souce code for the app and the slides html file with the tutorial - baiana/BMI-calculator-source-code ...

We rather fear that live syntax validation as you hand-code HTML is one answer to this, but on its own isn't sufficient. But we really wish it were – and we would be very happy to be wrong.