Here's one i just read........
How come there are 365 days in a year when there are 52 weeks, each week being 7 days........ 52 X 7 = 364
I have looked that up in the past
It is due to the Babylonians
They looked at the Mon and reckoned it went in cycles of about 30 days
which is rather too long for a decent cycle of work etc
so they rounded it down (??) to 28 days and had a couple of leap days to re-sync it every now and again
apparently
other civilisation followed that and wrote it down in their religious books to make it more authoritative
or - alternatively - God said it has 7 days and said so when He wrote the Bible (other religious books are available - as are other Deities)