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 		 [It may seem daunting to memorize a 24-million-digit number, but
with these tips youll be well on your way] [https://portside.org/] 

 HOW TO MEMORIZE THE LARGEST-KNOWN PRIME NUMBER  
[https://portside.org/node/19067] 

 

 Evelyn Lamb 
 December 26, 2018
Scientific American Blogs
[https://blogs.scientificamerican.com/roots-of-unity/how-to-memorize-the-largest-known-prime/]


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 _ It may seem daunting to memorize a 24-million-digit number, but
with these tips you'll be well on your way _ 

 , Kevin Dooley Flickr (CC BY 2.0) 

 

A few weeks ago, a computer owned by Patrick Laroche of Ocala,
Florida discovered a mathematical treasure,
[https://www.mersenne.org/primes/?press=M82589933] a new largest
known prime number. Known as M82589933, it has 24,862,048 decimal
digits. If you’d like to read more about it, check out this
article I wrote for Slate two years ago
[https://slate.com/technology/2018/01/the-worlds-largest-prime-number-has-23249425-digits-heres-why-you-should-care.html] (and
updated a year ago). Though I did not write that article about this
particular largest known prime number, I did write it about a previous
largest known prime numbers, and M82589933 is yet another verse of
the same song.

Today, I want to help you experience this new prime number viscerally
by memorizing it.

I don’t know about you, but there’s no way I’m memorizing a
24,862,048-digit number. Instead, I’m going to memorize an easier
82,589,933-digit number using the magic of binary. The newest prime is
a Mersenne prime [https://en.wikipedia.org/wiki/Mersenne_prime],
meaning it is one less than a power of two. In binary, numbers are
written using only the digits 0 and 1. One is 1, two is 10, three is
11, four is 100, five is 101, and so on. Any power of two is a 1
followed by some number of zeroes. We saw that two is 10 and four is
100. The pattern continues: eight is 1000, sixteen is 10000, and so
on. In base ten, if you subtract 1 from a 1 followed by a bunch of
zeroes, you get a bunch of nines. (E.g. 1,000-1=999.) In base two,
1000-1=111. Any number one less than a power of two is a string of
1’s.

The new prime number is 282,589,933-1. In binary, that is a string of
82,589,933 ones. Easy peasy. The difficult part of memorizing it is
keeping track of how many ones there are. Buckle up because I have
some ideas for that, too.

In the first place, we do need to memorize the number of binary digits
this number has. That’s 82,589,933. Try this handy phrase:
“Cabbages in April besmirch September asparagus. And how!” The
number of letters in the word correspond to the digits of the number,
and it’s easy to remember because April cabbages are indeed better
than September asparagus (in the northern hemisphere).

Now that we’ve memorized the number of digits, it would be nice to
find a way to keep track of where we are in the digits as we start
writing or reciting ones. The word TWENTY NINE is made from 29
straight line segments. Thus, it is an elaborate way to write the
number 29 in tally marks. I decided to expand on the idea. First, I
looked for famous poems or phrases that use no round capital letters.
The Declaration of Independence, the Gettysburg Address, “The Waste
Land,” and “The Jabberwocky” all disappointed me immediately. It
was clear: I had to create my own. The following is a poem I wrote to
help you get through it all. When written in capital letters, the poem
uses 500 straight line segments (punctuation is not included).

Amenity twenty nine:
Lie lazily,
a fizzy affinity
familial, alien
with hymnlike alkalinity.
We twelve examine finality.
The lake,
a wink,
an inky inlet.

Exit we the fiftieth line,
Tie a tiny thymey tine.

Waltzlike I talk.
Timelike we walk.

If you wish to write the new prime number, you can write this poem in
block letters 165,179 times--each straight line segment is a number
1--and then add 433 more ones. Alternatively, if you wish to recite
the number, you can write the poem down 165,179 times while saying
the word "one" with every stroke and then say "one" 433 more times.

Some challenges still remain in memorizing M82589933. How do you keep
track of how many times you have written the poem? Do you get to take
bathroom breaks while you demonstrate that you have memorized the new
prime number? What happens if a larger prime is discovered while you
are still in the middle of writing this one down? I am confident you
will find innovative ways to tackle these challenges and revel in the
full splendor of M82589933.

_Evelyn Lamb is a freelance math and science writer based in Salt Lake
City, Utah._

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