One of the perks of studying undergrad physics at MIT was taking third-semester quantum mechanics from someone who had an honest-to-god Nobel Prize. He (who shall remain nameless) was doing a test prep session with the class one night and at one point got to an expression that looked like this:
… at which point he stares hard at the board, then looks at us (~50 senior physics majors). Then at the board. Then us. Then back to the board, where he (a little sheepishly) reduces it to:
When we all got done laughing he retaliated with:
"Look. Experimentally, we don’t know the value of this number [points at alpha] better than within 2 orders of magnitude, and nobody can think of a way to measure it any better. The difference between pi and 3 is 5%. The simpler expression is going to hold true enough for some time between 50 years and forever. So shut up."