Knowing the correct order of magnitude is seldom trivial. Getting the correct order of magnitude quickly will make you a better decision maker (not to mention

Knowing the correct order of magnitude is seldom trivial. Getting the correct order of magnitude quickly will make you a better decision maker (not to mention impress people whose opinion matters). An imbalance of supply can increase/decrease the population by maybe as much as 2x (or .5x). An order of magnitude can be the difference between a market that's worth considering and one that's too small to currently be serviceable. This is important because in business getting a right(ish) answer quickly is often more important than getting a precisely correct answer slowly. While you're measuring precise supply and demand, FermiCo has already concluded that the market is too small and moved on. p.s. irregardless is a great word.