What's the Most Useful Thing You've Memorized?

You can download most of the original sources on the free books page. If anyone finds any inaccuracies, let me know. :slight_smile:


My wife has a part-time Etsy business that has me running to the post office to mail her products multiple times a week. Lately, I’ve decided I wanted to memorize the names/addresses of her customers, since I’m always required to verify addresses at the P.O. So, as each new order comes in, I’m adding that person’s name/address to a dedicated memory palace.

So far it’s helped at the post office and at home, since it’s nice to be able to talk somewhat intelligently with my wife about her business.



I think your criticism of the Wikipedia page is on the mark. In general I consider it a high quality resource but not invariably. This is a weak page.

Wikipedia is too often a victim of the Bad Dollar Bill Fallacy. Some dollar bills are counterfeit. For all you know any dollar bill could be a forgery. Dollar bills are not to be trusted and the currency is worthless.

As a history of the Major System it is surely deficient, but the citation of Herigone in the 17th century does establish that it’s at least that old and predates Harry Lorraine.

I wonder what the original language was? My guess is Latin which was the language of scholarship at that time. English would have been very unlikely.

Absolutely. My original reply was meant to clarify why someone might assume Lorayne came up with it after reading The Memory Book, since Lorayne never uses the words “Major system” when describing it or explains that it isn’t actually his personal creation.

I was particularly struck by this when reading a research study that referred to it—by people who should have known better—as “Lorayne’s ‘Figure’ system.” So, when echoreflection here referred to it as “Lorayne’s phonetic alphabet,” it sparked my response.


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Although this article does not give a specific source for the information, other than the 6-volume work for which he is best remembered (written in both Latin and French, apparently) it does credit Herigone with inventing the system: http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Herigone.html.

And my apologies to anyone who wonders how this thread got so thoroughly hijacked! :slight_smile:


For contractual purposes, my company needed to get several of us Comptia Security+ certified. My travel schedule prevented me from being on the initial list of employees. The others, they gave about three months to study and prepare.

Then, less than a week before the test, I was asked to go ahead and take it as my travel plans had changed. I was travelling home on a 26+ hour overseas trip.

Fortunately, my background and experience helped tremendously. But there were port numbers, encryption details, acronyms, and other items I needed to be able to pull out of the air. I finished reading a Security+ book on the flight, making notes of what I needed to memorize.

I put everything I needed into a memory palace. I not only passed the test, I got the highest score from my company.

That was the most useful thing on the spot. Another useful thing that only involves a small amount of memorization is the Doomsday Algorithm. With it I can give the day of the week for any date, future or present.


Like @echoreflection, the Major System. My original interest in this site and still my main purpose was to develop my mental arithmetic skills which have always been weak. But once acquired it has proved useful in all sorts of ways. It has made numbers seem more friendly, more interesting and less anonymous. Numbers have gone from being fussy annoying details, to fascinating details.


Doomsday Algorithm? Would you say more about that, please and thank you.

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First thing I did after discovering these techniques was make a two digit pal. I’ve since memorized 100 digits of pi as well as 0-100 in French in Spanish. I’ve also memorized a bunch of poems which has been immensely enriching. If I’m ever bored I can just look in on any classic poem or story I want it’s great. Thanks to Ed Cookes book I also have the kings, the prime ministers and the presidents.


Glad to. I even wrote a book about it, though I’m pretty sure forum rules prohibit me linking to it here. Look it up on Amazon and you’ll find it. :slight_smile: It’s got the name right there in the title. And it’s the second book in a series.

This website gives an overview.

It’s part basic arithmetic, and simple memory.

The idea is that there are certain dates that fall on the same day of the week, no matter what the year is. It could be any day of the week, but it’s always the same. The easiest to remember are 4/4, 6/6, 8/8, 10/10, and 12/12. For this year (2019) they all fall on a Thursday.

You begin by calculating the day of the week, known as the Doomsday, that these Anchor days fall on.

To do that you need to know these things first:

Weekdays as numbers
• Sunday = 0
• Monday = 1
• Tuesday = 2 (Twos-day)
• Wednesday = 3
• Thursday = 4
• Friday = 5
• Saturday = 6

The anchor day for the century:

(Yes, I know the century actually begins on the 1. 1801, 1901, etc. Doesn’t matter to the method. In fact, it’ll mess you up.)
• 1800 – 1899: Friday (or 5)
• 1900 – 1999: Wednesday (or 3)
• 2000 – 2099: Tuesday (or 2) Two-thousand
• 2100 – 2199: Sunday (or 0)

This keeps repeating 5-3-2-0, 5-3-2-0. 1700s is a 0. 2200s is a 5. And so on.

At least one Anchor day for each month
(Dates given in US Form. 1/3 = Jan 3.)
1/3 on non-leap years. 1/4 on leap years.
2/28 on leap years. 2/29 on non-leap years.
10/31 (Halloween)

The last day of February is easy to remember. The other even months are very easy to remember. so is March 14, as in US form it is 3/14. Pi day.

For the other odd numbered months, aside from January, there’s a mnemonic I haven’t been able to improve upon. The dates are 5/9, 9/5, 7/11, 11/7. “Working from 9 to 5 at the 7-11.”

You can figure out other dates as well. For instance, the week is 7 days long. November’s anchor date is on 11/7. That means 11/14, 11/21, and 11/28 are also anchors. For that matter, so is October 31.

You also need to know if it’s a leap year or not.

From there it’s a relatively easy calculation. You remember four numbers and do simple calculations with them. I’ll copy and paste from my book. It’s not plagiarism, since I wrote it. And it’s less than 10% of the book, so it’s fine with Amazon as well.

First Number: How many times does Twelve fit evenly into the last two digits of the year? Remember this number.
Example: April 6, 1975.
Twelve goes into 75, six times. This is because 12 X 6 = 72.
In our example, we are remembering 6.

Second Number: What is the difference between the two-digit year and the product of the first calculation?
Example: April 6, 1975.
We’re already remembering the number 6, for the number of times 12 evenly goes into the two-digit year, 75.
We also know that 12 X 6 = 72. Now we subtract the year from the product. In this case, that means 75 - 72. The answer is 3.
We are already remembering 6 as our first number. Now we also add 3 to our short-term memory. Repeat to yourself, “6, 3.”

Third Number: How many times does the number 4 fit evenly into our second number?
Example: April 6, 1975.
The second number for this example was 3. This makes our third number easy. Four goes into three 0 times.
We remember 0 for this. That makes our numbers 6, 3, and 0.

Fourth Number: What is the century’s Doomsday?
Example: April 6, 1975.
This is a number you don’t have to calculate because you’ve already memorized the Doomsdays for centuries. In this case, for the 1900s, the answer is 3.
That leaves our four numbers to remember as 6, 3, 0, and 3.

Add the Four Numbers Together:
Example: April 6, 1975.
You might be tempted to add the numbers as you go, leaving yourself with just one running number to remember.
The issue with this is you’re doing calculations with the numbers, making it easy to get confused. Better to add them at this step.
For our example, we have 6 + 3 + 0 + 3 = 12.
And as a bonus, you no longer have to remember the four individual numbers. Just know this sum for as long as it takes you to do the next step.

Reduce by a Factor of 7:
Example: April 6, 1975.
What we are doing here is lowering the number until it’s in the range of 0 through 6. These are the weekdays we’ve memorized.
There are several ways to count at this point. The more practice you do, the more you may see patterns, and limit the number of times you have to reduce.
For now, our sum from the previous step was 12.
12 - 7 = 5.
5 = Friday.
We now know the Doomsday for 1975 was a Friday.

Count Up or Down to the Date:
We’re nearly there. You take the closest anchor day to the date you’re calculating. April 6 is just two days off from April 4, or 4/4.
Since we know 4/4/75 was a Friday, we add two days, and get Sunday.


Can you pm a link to the book? I would love to get a guide I can loan out!

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@Walt, I just sent it.

Also thought of something else. I haven’t done this yet, but memorizing the Time Zones across the globe could be useful. Especially since I travel for a living. Has anybody done this? Any thoughts? I’m thinking of making a Memory Palace, and storing the name and the offset in each area.

What’s the Most Useful Thing You’ve Memorized?

At my work we have a Mission statement for the company which is expected to be known to every employee and all our actions should be governed by taking that Mission statement as our True North.

I wanted this Mission statement to be retained verbatim in my mind. So using the tips provided by Mnemotechs (Is this a word? I do not know, I want a word for person/mentor who evangelizes Memory Techniques) I created a Memory Palace Journey using our company office as location.

Why retain the Mission Statement in Memory? It is not needed and not expected for an employee to recite verbatim, but now as I know it verbatim and can recollect and revise any time. I can weight each and every action I take for work on the anvil of this Mission Statement.

Trust me that this has changed the way I work and it has given more clarity to my work life as we want to remain aligned with the company Mission statement all the time.

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Something along the lines of this maybe? I’ve created this one a while ago…

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@tusharvjoshi, that’s an excellent idea. I bet you’re the one that can say it word-for-word. How long is it?

@bjoern.gumboldt, not exactly. But close. I’m going to learn the UTC offset, the daylight saving time rules for the areas that adhere to it, and at least one location for each UTC. Debating whether to learn all 390 Time Zone variations (for instance, there’s 15 that are UTC 0) or just one for each UTC, which would be only 38.

Probably I’ll do the latter, at least starting out. It should be sufficient for my purposes. I was surprised at how much research this involves. I planned just to look up a list and memorize it.