i'm workign through agile web dev with rails. i understand the scaffold and that it generates forms based off of your db definitions.

i'm curious how one would structure an app (or portion thereof) that didn't use a db? let's say i wanted an input box like so...

Enter Number: [text box here]

[Enter link here]

i would then like it to then display a different page with the number multiplied by 2. i know the math s/b stuck in the controller. i think ruby has a post method, but i don't know how to use it.

how would i display the result in the same page?

general answers with code snippets would probably be sufficient.