There is a static object named 'Math' in JS with many built in properties and methods.
You'll want to investigate this further whenever you're manipulating numbers. Check MDN documentation before writing your own functions, because they may already be defined there.
Examples include Math.random() which will return a random number in a given range and Math.round() which will round the input to the nearest integer.
I used Math.random() when I built the random quote generator for the Free Code Camp front end development project.
When you're working with numbers, you should also be aware that JS has an interesting attribute called 'floating-point format'.
Depending on the amount of numbers, the size of those numbers, and the number of computations, JS may return something that is inaccurate by .00004.
There are ways around this, and in general it doesn't pose issues, but it's something you should be aware of in the event you run into some problems that aren't making sense.