GeoGebra Worksheet

GeoGebra makes building JavaScript or HTML5 applets a piece of cake.

I recently wrote a quick program to dynamically "analyze" the effect of additional monthly prepayments on a loan, on the amortization schedule. The formulae are available on this wikipedia page.

Here is a link to the GeoGebra worksheet on GeoGebraTube. You can download the file, or merely play with it in (either JavaScript or HTML5).