Ummm...and are we supposed to guess what the calculator does? Or what it looks like?
Then start putting the JS code in the page (at the END of the page, just before the </body> tag, will be both best and easiest).
And not to ask a silly question, but... Why would you need to convert ALL pages to ASP.NET? Why couldn't you just convert the one page that has the calculator on it?
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.