NaN being falsey leads to interesting statements

NaN is a javascript constant representing something that is 'not a number', and like almost everything else in javascript, its falsey.

Boolean(NaN)
> false

You can determine if a number that is passed to a function is valid after you give it to a mathematical operation.

function doSomething(number) {
  var importantNumber = number * 96 || 100;
  console.log(importantNumber)
}