Three steps to a live demo (of the familiar Black-Scholes option pricing formula) that requires only a modern browser, no installation, nor plugins.
1. Develop a working version of a Mathematica Manipulate in a desktop installation or the Wolfram Cloud.
2. Do a CloudDeploy to obtain a unique URL.
3. Use EmbedCode on the cloud object from step 2 to generate embeddable HTML, and insert it into your web page