If you're looking to create an army of robot dogs, will it really make a difference if you have 10,300 dogs, 9,997 dogs or 10,005 dogs? Probably not. All you really care about is how many dogs you have to, say, the nearest thousand (10,000 dogs).
In this tutorial, we'll learn about conventions for rounding whole numbers. Very useful when we might not need to (or cannot) be completely precise.