I've never tried the PAO system, due to the startup costs of pre-memorizing 100 person-action-objects.
But a simpler alternative which requires less work up front is the Major System (sometimes called the Phonetic system) [0].
The way it works it by assigning each digit a sound-value (or family of sounds). To remember a number, you then convert the digits to the letter-sounds, and fill in vowels that don't have a digit value to create words.
E.g. to remember Boltzmann's constant, I do this:
1.38 x 10^-23
1 has the letter value "t" or "d". So I use the word "tea" ("e" and "a" have no digit value), to remember the digit 1.
The 38 is converted to "m" and "v", which becomes "movie".
23 becomes "n" and "m", or "nemo", the fish from Finding Nemo.
Putting it all together it becomes: Ludvig [1] walking on bolts (= Ludwig Boltzmann), and in his right hand he's holding a old VHS movie on top of which balances a cup of hot tea. In his left hand he holds a frozen (to indicate the negative sign in the exponent) Nemo.
To make it memorable you can make this scene as vivid as possible: Ludvig is a cautious character who sniffles a lot; walking on bolts would hurt and make it difficult to balance the cup of tea on top of the movie; the frozen fish would be cold and slippery in the hand; the tea would smell nice; etc.
I remember phone numbers and long digits of numbers by their position on a number pad. Don't know why this is easier for me, but remembering the pattern my finger would trace tapping in a sequence of digits just pops in my memory with ease. So I have to mentally retrace the pattern to figure out what the actual digits are.
I'm fascinated by memory, yet I've never been able to make any progress with any of these memory systems that involve artificial indirection.
I don't think in a spoken language, so if I have to memorize a word it ends up being the concept, and I pull it out as a cluster of synonyms, and then I also need an out-of-band way to memorize which of the synonyms it is. I really don't know how actors memorize lines.
I also can't visualize a complex artificial scene all at once. That's lots of extra things to memorize before I can get to the thing I want to memorize, and figuring out a way to remember these zany scenes is harder than just memorizing the numbers themselves! Numbers are easy. There's no possible synonyms for "8".
For phone numbers, 95% of my contact list has the same area code, so they're really only 7 digits. That's the same as a license plate, and I pick those up just by looking at them a few times without really trying. I'm not disparaging anyone who can make this system work -- I'm impressed! It just seems like a lot more work than necessary, if the goal is merely to memorize 10 or 20 phone numbers.
Caveat: requires usage of English language. Useful if you (mostly) think in English. Otherwise, if English is not your native language nor your primary language then I expect this application to be problematic. Has anyone falling under such circumstances tried it?
Also, too bad (for the application) that the need to remember phone numbers is no longer high.
I was hoping this was going to be a lighthearted piece on how it's funny how we don't remember phone numbers anymore.
It turned out to be very weird. Why would you need a system for remembering phone numbers? Before cell phones, I easily had dozens of phone numbers in my head: family, friends, even things like the local pizza shop. Everyone I knew had similar recall. We didn't try at this; it just came out of simple repetition.
If you want to memorize phone numbers, write them down on a small piece of paper and stick it in your wallet. When you need to call them, consult the list, and enter the numbers manually, not by rote, but while actually thinking about the numbers as you enter them. Assuming you call them enough, you'll have the numbers down within a few weeks, a month at the outside. If you don't, then perhaps you don't really need to memorize them in the first place?
These days I know two relevant phone numbers: my own and my sister's (and only because hers is similar to one of my prior phone numbers). I also remember the home phone number for where I lived until I was six years old, and a few other old ones. Oh, and I remember my (fixed, publicly-addressable) IP address from my freshman year of college (20 years ago). I kinda wish I could evict those old numbers and make room for something else.
I had an amazing memory when I was a kid (now I have good memory, but less than exceptional). As an example, I knew by memory ~300 phone numbers. To this day, 30 years later, I still remember 60-70 of these.
The book "Moonwalking with Einstein" was my first introduction to memorization techniques. I had no idea these techniques existed, much less there were competitions for them. I drove my wife crazy trying to impress her with memorizing pi to 100 digits and memorizing a deck of cards. She was not impressed...I moved on to the next hobby.
But a simpler alternative which requires less work up front is the Major System (sometimes called the Phonetic system) [0].
The way it works it by assigning each digit a sound-value (or family of sounds). To remember a number, you then convert the digits to the letter-sounds, and fill in vowels that don't have a digit value to create words.
E.g. to remember Boltzmann's constant, I do this:
1.38 x 10^-23
1 has the letter value "t" or "d". So I use the word "tea" ("e" and "a" have no digit value), to remember the digit 1.
The 38 is converted to "m" and "v", which becomes "movie".
23 becomes "n" and "m", or "nemo", the fish from Finding Nemo.
Putting it all together it becomes: Ludvig [1] walking on bolts (= Ludwig Boltzmann), and in his right hand he's holding a old VHS movie on top of which balances a cup of hot tea. In his left hand he holds a frozen (to indicate the negative sign in the exponent) Nemo.
To make it memorable you can make this scene as vivid as possible: Ludvig is a cautious character who sniffles a lot; walking on bolts would hurt and make it difficult to balance the cup of tea on top of the movie; the frozen fish would be cold and slippery in the hand; the tea would smell nice; etc.
[0] https://en.wikipedia.org/wiki/Mnemonic_major_system [1] https://pbs.twimg.com/profile_images/525793520662380544/w9GJ... A character in an iconic Norwegian film.