> he was able to work it out in his head, and pretty quickly
That's a scary ability. I wonder if that guy is equally adept at converting acre-feet to gallons, or if he's a one-trick pony.
Here's what I know without looking anything up: 1 mile = 1760 yards, 1 yard = 3 feet, 1 foot = 12 inches; 1 US gallon = 231 cubic inches (exact conversion, and a weird number at that). So 1 cubic mile = (63360 inch)^3 = 7707820032000/7 gal ≈ 1.101 trillion US gallons.
Fun fact, combustion engine displacements used to be quoted in cubic inches. Note that 61 in^3 ≈ 1 litre.
That's a scary ability. I wonder if that guy is equally adept at converting acre-feet to gallons, or if he's a one-trick pony.
Here's what I know without looking anything up: 1 mile = 1760 yards, 1 yard = 3 feet, 1 foot = 12 inches; 1 US gallon = 231 cubic inches (exact conversion, and a weird number at that). So 1 cubic mile = (63360 inch)^3 = 7707820032000/7 gal ≈ 1.101 trillion US gallons.
Fun fact, combustion engine displacements used to be quoted in cubic inches. Note that 61 in^3 ≈ 1 litre.