Mnemonic for the number of days in each month

I was taught as a kid to use the knucke mnemonic [0]. Easy to use, and doesn't take much thought outside of counting the months

[0] https://en.wikipedia.org/wiki/Knuckle_mnemonic

Also in case you did not know, the leap year is not on even hundreds of years, i.e. 1900 was not a leap year, and neither will 2100 be under the current calendar.

The exception is every four hundred years, which means 2000 was a leap year, as would 1600 have been, and 2400 will be.

This means the year is on average 365.2425 days long[1] -- a constant that I've found surprisingly useful to memorise.

[1]: Because 365 + 1/4 - 1/100 + 1/400.

The number of days in a month sits in a nice space of complexity for me - it's hard enough to be non-trivial, but simple enough you feel you should know it.

Probably the easiest thing to remember is that short and long months generally alternate (the exceptions are December/January, and July/August).

I like the 'use the knuckles of your hands' technique - put your hands next to each other, and count the months using your knuckles and the spaces - so January (knuckle - high so long-month), February (space - low so short-month), March (knuckle - high so long-month). When you reach July, you get your left-and-right knuckles next to each other, so two long months in a row. [EDIT: I can now see that I'm about the fifth person to mention this!]

Back in primary school the knuckle method that we were taught seemed too complex and slow, so I made up a word instead from the 30-day months: "apjuseno".

> In numeric format, these months correspond to 4 6 9/11.

Easy to remember for Romans: IV VI IX XI (”if you write the month number with two letters that aren’t identical”). I think that worked under the Julian calendar (https://en.wikipedia.org/wiki/Julian_calendar#Table_of_month...)

In Portugal (idk about other countries) we use something like: - Use knuckles and spaces between them - Start with left-most pinky knuckle (in - Count across hand: knuckle (31), space (30), knuckle (31), etc. - Jump to right hand's index finger knuckle after left index (so it's two times knuckle, when passing from left to right hand (for July and August) and continue.

February is special: 28 or 29 days

My wife makes a fist and counts her knuckles and divots on her left hand:

pinky Jan 31

divot Feb (28/29)

ring March 31

divot April 30

middle May 31

divot June 30

pointer July 31

(now head back the other way)

pointer August 31

divot September 30

middle October 31

divot November 30

ring December 31

I don't know where she learned it, but it's genius.

I thought I was the only one who still hadn't figured this out

feb apr jun sep nov

fapjunseno