And then we have a prime number of months. Checkmate OP

Congrats you invested invented International Fixed calendar - https://en.wikipedia.org/wiki/International_Fixed_Calendar

Edit: typo

FYI, there is kind of a push toward this, usually by landlords and other bill collectors, who would just love to be able to charge an extra month of rent or bills each year.

There's no way in Hell under the current leadership in many parts of the world that bills would be multiplied by 12, then divided by 13, and then capped at that. The cap wouldn't work anyway. The only responsible way to do it would be to charge bills on an annual basis, and divide it by the "number of months" for the "convenience" of the consumer. Then it would just be set up to where all the monthly payments would go down. But yeah, no way they enforce that.

That's metric months.

Yes, Augustus. But they didnt add months; they renamed existing months, and also got days added to them by taking off from the last month - which was February at that time. Related fun fact: September, October, November, and December are just names from the root words in Latin for 7, 8, 9, and 10 because they were the 7th, 8th, 9th and 10th months. When the calendar was rearranged to start with January, it threw that off.

The Roman calendar originally didn’t last all year round. It began in the spring and ended at the start of winter, and then the winter period just didn’t exist on the calendar.

Calendars were invented to plan the growing of crops, so tracking the days in winter didn’t have any purpose, so they left winter out.

Babylonians divided their lunar months into 4 weeks, the number seven was significant as the number of celestial bodies they could see other than non-moving stars. It wasn't until later that the seventh day got any association with resting.

I read about it in a few places it this sums it up: https://www.scienceabc.com/eyeopeners/why-do-we-have-seven-days-in-a-week