This example demonstrates simple JavaScript function definitions and invocations, displaying results in separate HTML paragraphs. It shows both standard function declarations and function expressions assigned to variables, each performing multiplication. A third function, `mycalc`, sums two numbers but is never called. The page uses plain HTML elements with IDs (`demo1`, `demo2`, `demo3`) and a CSS class for large, centered text, with all logic handled in an external `learn.js` file without any external libraries.