[ordu]

> A mile is 5,280 feet and a kilometer is approximately 3,280 feet.

Wow, I didn't think of poor imperial kids, that are definitely forced to remember all these numbers. But now I'm really sorry for them.

    $ factor 5280
    5280: 2 2 2 2 2 3 5 11

2^5 and 5 is nice, 3 can be tolerated, but 11? Who in their right mind would come up with something like this? Why not just round it to 5000?

[ahazred8ta]

Up until 1300, the old foot was longer and the mile was 5000 feet. In 1300 they redefined 10 old feet to be 11 new smaller feet, an acre was now 66x660 feet instead of 60x600, and eventually the mile was 8x660 = 5280.

[QuercusMax]

In practice these are just big numbers you memorize. 5280 feet in a mile, 63360 inches in a mile, 1760 yards in a mile...

It's not like you often have to do math with them, outside of school math problems. A year isn't precisely 365 days, and months are all different lengths. It's just more of the same type of thing; doesn't actually cause problems when distances are usually expressed in miles anyway.

[remram]

From polling my American friends, ask them how many yards in a mile and they'll answer 5280. They don't really know how the system work and can only vaguely remember (one of) these numbers.

The system is not meant for units to be converted.