Dynamically update total through dropdown
===

i have a bit of a dilemma, i am trying to make it so that when a user selects an option from a dropdown box it dynamically updates a total on the same page, without any reloading.

In other words i have 5 different options in a dropdown box (1,2,3,4,5) and if the user selects 1 it needs to put it through a simple equation, and then output it in a "total" box on the right, the problem i want to do this dynamically with no reloading, can anyone give me any advice or tips on what i should be using and any tutorials that might help (code etc...)

Thanks