"The difference between mathematicians and physicists is that after physicists prove a big result they think it is fantastic but after mathematicians prove a big result they think it is trivial" — Lucien Szpiro
Here's a good mnemonic to convert Miles to Kilometers using the Fibonacci numbers (1,1,2,3,5,8,13,21,...):
3 mi ≃ 5 km
5 mi ≃ 8 km
8 mi ≃ 13 km
Also the ratio between 1 mi and 1 km is very close to the Golden Ratio ≈ 1.61 🧐