You're viewing a single thread.
I can read UPC, ISBN, and EAN bar codes. Tear the numbers off the bottom, hand me the lines, and I can tell you the numbers you tore off. Also, if you give me any specific date on the Gregorian calendar (on or after October 15, 1582), I can tell you the day of the week it was or will be on.
Finally...way less interesting...but I have a Master's degree in math and have taught elementary, middle school, high school, dual credit, and college math classes.
You've memorised the Doomsday algorithm?
Indeed.
July 26, 6.000.002.024
It's a Friday. Because all that matters in any date with a year greater than four digits is the last four digits, and July 26, 2024 is today, and today is a Friday. 😊
But, if I didn't know July 26, 2024 were a Friday...
Step 1)
Starting numbers:
- Century is a multiple of 400: 2
- Century is 100 more than multiple of 400: 0
- Century is 200 more than multiple of 400: 5
- Century is 300 more than a multiple of 400: 3
2024 is in the century of the 2000s. 2000 is a perfect multiple of 400, so the starting number there is 2.
Step 2) 24 is a multiple of 12, specifically 12 x 2. Thus we add 2.
Step 3) 24 is a perfect multiple of 12 with zero years in excess, so we can add 0.
Step 4) There are no leap years in the 0 extra years beyond the closest multiple of 24, so we can add another 0.
Step 5) The Doomsday for July is 7/11. July 26th is 15 days after July 11th. 15 mod 7 is 1, so we add 1.
Step 6) 2 + 2 + 0 + 0 + 1 = 5
Step 7)
- 0 = Sunday (Noneday)
- 1 = Monday (Oneday)
- 2 = Tuesday (Twoday)
- 3 = Wednesday (Threesday)
- 4 = Thursday (Thorsday Foursday)
- 5 = Friday (Fiveday)
- 6 = Saturday (Sixaday)
Our total was 5, so the date July 26th, 2024 (or any year with the last four digits 2024) is a Friday.
What should also probably matter though is the existence of the sun 😉 Otherwise, how can it be a day?
To be fair though, I gave that point in time a day-like notation
I edited my response to show the math behind it. And well played with the astronomy fun, didn't even notice it. I am a math teacher with autism IRL, so I hyperfixated on the numbers!