EXAMPLE 2 – Dec. 25th, 2023

• 2023’s code is a 1

• December’s month code is a 3

• 25th is a 25, but dividing it by 7 and taking the remainder gives you 3 remainder 4, so 4.

  • NOTE: You can do the dividing by 7 as you go through each step or wait till you have the final total at the end. It doesn’t matter! I personally like to get rid of big numbers along the way, so I do it in stride.

• That’s 1+3+4 = 8. Again, divide by 7 and take the remainder, that’s 1 (Monday).

• Christmas Day in 2023 will be a Monday!

Pretty sweet, right? Now for the next few years you won’t ever have to check a calendar, you’ll know almost instantly what day of the week a certain date falls on.

NOTE: One small detail you’ll have to keep in mind are leap years (a year where there is one extra day in the calendar year). The most recent leap years have been in 2016 and 2020. The next one will come again in 2024. For those cases, you need to subtract 1 ONLY IF your month is January or February. To know if any year is a leap year, the 2-digit year ending needs to be divisible by four (that means you can half it twice perfectly). If it’s a century year (like 1700 or 2000, you also need to check if the full number is divisible by 400. So 2000 was a leap year, but 1900 was not).

ALL THE CALENDAR DATES

Now what if you want to do any year in history? There is a way to do this, but requires a little more memorization and math. Technically the Gregorian Calendar that we know so well only started in the late 16th century, so anything before that doesn’t really make sense, but we can still apply the following method regardless.

There is a simple code list you need to learn for the century:

• 1600s – 0

• 1700s – 5

• 1800s – 3

• 1900s – 1

• 2000s – 0 

• 2100s – 5

It repeats every 4 years in case you want to keep going into the future and/or past. The reason we were able to do 2016-2020 in our examples in above without including this code was because the 21st century (2000s) is a 0, so we ignored it in our calculation. But this isn’t the case for other centuries. But, um… yeah, you probably don’t really care too much about what day of the week your birthday falls on in the 22nd century, right? Ha!

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Also, we need to memorize a list for every 2-digit possible year number. In the examples above, I gave you the codes for years that ended in 19, 20, 21, 22, 23, and 20 (just to get you started for some of the more recent 21st century years), but we need to know all 2-digit year endings. That may sound tricky, but it’s not. There is, alternatively, a way to calculate this on the fly, but I honestly think memorizing them is faster and much easier (and heck, you’re a memory expert by now anyways, so why not?). Here is the list categorized by similar code:

• 0 – 05, 11, 16, 22, 33, 39, 44, 50, 61, 67, 72, 78, 89, 95

• 1 – 00, 06, 17, 23, 28, 34, 45, 51, 56, 62, 73, 79, 84, 90

• 2 – 01, 07, 12, 18, 29, 35, 40, 46, 57, 63, 68, 74, 85, 91, 96

• 3 – 02, 13, 19, 24, 30, 41, 47, 52, 58, 69, 75, 80, 86, 97

• 4 – 03, 08, 14, 25, 31, 36, 42, 53, 59, 64, 70, 81, 87, 92, 98

• 5 – 09, 15, 20, 26, 37, 43, 48, 54, 65, 71, 76, 82, 93, 99

• 6 – 04, 10, 21, 27, 32, 38, 49, 55, 60, 66, 77, 83, 88, 94

As you can see, there are seven possible codes, 0-6 and the years associated with that particular code. My recommended way of memorizing these is by choosing seven big memory journey rooms. Then, with your PAO person, imagine the person matching the code (or room) hanging out in that room. For example, room 0 (perhaps your kitchen, for example), we would picture Abe Lincoln (05), Andre Agassi (11), Arnold Schwarzenegger (16), and everyone else on that list, interacting and living in that room . That way, when you see a 2-digit year, you’ll instantly remember what room they were in and remember the code associated with that room (just make sure to somehow LINK the 0-6 code digit to the room, so you know which room is which number).

OKAY, then what? The process is the same as before except you’re adding two more numbers, the code for the century and the code for the year. Let’s do an example for the whole she-bang:

EXAMPLE 3 – August 2nd, 1829

• 1800s’ century code is a 3

• 29’s year code is a 2

• August’s month code is a 0

• 2nd is a 2

• Add it all together (dividing by 7 when you spill over):

  • 3 + 2 + 0 + 2 = 7, dividing by 7 and taking the remainder gives you 0 (Sunday)

• August 2nd, 1829 was a Sunday!

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EXAMPLE 4 – July 4th, 1776

• 1700s’ century code is a 5

• 76’s year code is a 5

• July’s month code is a 4

• 4th is a 4

• Add it all together (dividing by 7 when you spill over):

  • 5 + 5 + 4 + 4 = 18, dividing by 7 and taking the remainder gives you 4 (Thursday)

• July 4th, 1776 was a Thursday!

And now you know: the Declaration of Independence was signed on a Thursday!

Let’s do a few more example, so you get the hang of it:

EXAMPLE 5 – February 18th, 1984

• 1900s’ century code is a 1

• 84’s year code is a 1

• February’s month code is a 0 (it’s usually 1, but 1984 was a leap year, so we subtracted 1)

• 18th is a 4

• Add it all together (dividing by 7 when you spill over):

  • 1 + 1 + 0 + 4 = 6, dividing by 7 and taking the remainder gives you 6 (Saturday)

  • NOTE: if your answer is smaller than 7, when dividing by 7 and taking the remainder you’ll get 0 remainder whatever your number is. TL;DR: if your answer is smaller than 7, your final answer IS that smaller number! EASY!

• February 18th, 1984 was a Saturday!

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EXAMPLE 6 – October 21st, 2015

• 2000s’ century code is a 0

• 15’s year code is a 5

• October’s month code is a 5

• 21st is a 0

• Add it all together (dividing by 7 when you spill over):

  • 0 + 5 + 5 + 0 = 10, dividing by 7 and taking the remainder gives you 3 (Wednesday)

• October 21st, 2015 was a Wednesday!

Also, this was the day Marty McFLy went Back To The Future!

EXAMPLE 7 – May 29th, 1953

• 1900s’ century code is a 1

• 53’s year code is a 4

• May’s month code is a 6

• 29th is a 1

• Add it all together (dividing by 7 when you spill over):

  • 1 + 4 + 6 + 1 = 12, dividing by 7 and taking the remainder gives you 5 (Friday)

• May 29th, 1953 was a Friday!

This was also the historic day that Tenzing Norgay and Edmund Hillary first summited Mt. Everest. I guess Friday’s are great for big adventures!

How do you feel about this calculation now? Not so bad, right? If you have any other questions about it, feel free to send me a message at nelson.dellis@gmail.com. Thanks!

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