Do you remember the colours in the spectrum by chanting 'Richard of York Gained Battles in Vain'? Have you ever made an L-shape with one hand to differentiate between left and right? Or do you just rely on a knot in your handkerchief or a piece of string on your finger?

Though elephants are reputed to never forget, humans aren't so fortunate. Many of us resort to using little tricks to jog our memories, whether it be to recall the names of the kings and queens of England or simply not forgetting your nearest and dearest's birthday. Such aide-memoires are often called mnemonics¹ But what are the best mnemonics?

For this particular Topic of the Week, the h2g2 Community went mnemonic crazy. No really, they did.

For the Planets

To remember the order of the eight planets from proximity to the Sun (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) there is the traditional:

Men Very Easily Make Jugs Serve Useful Needs

Note that the first two letters match the planet name for many of these, which means it can distinguish between Mercury and Mars.

Before 2006, dwarf planet Pluto was also considered to be a major planet and the mnemonics reflected this. For example:

Mr Voyle Earns Money Just Shutting Up Noisy Pupils

Another way of learning the planets in the correct order is to learn this mnemonic:

My Very Excellent Method: Just Say You Know Planets

Another way:

I use this one with my pupils to help them remember the order of the nine planets starting from Mercury: 'My Very Excellent Mother Just Sent Us Nine Pizzas'. My = Mercury, Mars sounds like Ma which is Mother. I also add a twist - I teach them it using sign language as kinaesthetic learning!

And the German equivalent is: Mein Vater erklärt mir jeden Sonntag unsere neuen Pläne' - which translates roughly, 'Every Sunday my father explains our new plans to me. Doesn't make any more sense than the English ones, though...

Monkey Nuts

A cheeky wee mnemonic from a cheeky wee monkey:

As a kid I had trouble remembering the correct order of 'm' and 'n' in the alphabet - I used 'monkey nuts' as an aide memoire. I took 'monkey nuts' from the following rhyme:

I love bananas, monkey nuts and grapes, That's why they call me Tarzan of the Apes!

The Grade School Bunch

Here's some well-remembered stuff from school:

Please Excuse My Dear Aunt Sally

This helps us remember the order of operations in mathematics: Parenthesis, Exponents, Multiplication, Division, Addition, and Subtraction. And another great maths mnemonic is the following:

Some Officers Have
Curly Auburn Hair
To Offer Attraction

This represents:

Sin = opposite/hypotenuse
Cosin = Adjacent/hypotenuse
Tangent = Opposite/adjacent

My maths teacher made this up to help us remember how to work out Sine, Cosine and Tangent in triangles. Look at that, I remember the memory aid 16 years later. I've forgotten the spellings though. I also can't remember if they are divided by or multiplied by. Easier to remember than SOHCAHTOA that my previous teacher tried on us!

You can also use:

Silly Old Harry
Caught A Herring
Trawling Off America

Distinguishing Left and Right

One of the symptoms of Dyspraxia is not being able to quickly distinguish between left and right. The Japanese hold up an imaginary bowl of food and mimic using the chopsticks, flicking imaginary food towards the mouth. The chopstick hand is the right hand (or the left hand, if the person is left-handed).

Dyspraxia is a terrible curse (my father suffers from it - actually he has it, the rest of us suffer) and he has great difficulty knowing, quickly, which is left and which is right (as do I). What he does to remember is hold his hand out, palm down with the thumb at right angle to the palm, creating an 'L' for left...

Advice for Students Who Can't Remember Anything

This is a bit crude, but it does work:

Write all of your assignments on the inside of your wrist where you'll notice it out of the corner of your eye a lot. I always forget that I wrote it there and then look down and get a little reminder! This works best if you only have to remember one or two things at a time!

And this method of remembering is quite canny:

I always write things that I want to remember on revision cards, and stick them to the ceiling above me bed. Not only do I see the reminders/revision notes every time I go to bed and get up, but the labourious task of actually sticking the stupid things to the ceiling helps whatever it is that I'm trying to remember to stick in my mind.

Stars

Astronomers like to be able to classify stars. The usual method is to plot a graph of the star's (absolute) magnitude (ie, how bright it would be from a distance of 10 parsecs) against its temperature. The resulting graph is known as a Hertzsprung-Russell Diagram.

The majority of stars lie in a slightly wavy band, which runs from the top left of the graph to the bottom right. Using this as a guide, astronomers can predict the magnitude [temperature] of a star, given its temperature (magnitude).

However, the boffins like to classify things a bit more - the stars also belong to various Spectral Classes (related to the temperature). The main classes just have letter names - OBAFGKM. These are subdivided into tenths, with a numerical suffix to the letter (eg F6). But how do you remember the letters?

Oh be a fine girl [guy], kiss me!

Melodies

Song lyrics are learnt very quickly, and remembered for years and years. Phone numbers are remembered easier if they are said with a rhythm. If the rhythm is wrong, you might not remember.

I know the first few books of the New Testament to the tune of 'An English Country Garden'.

And this is really sweet:

Red for the rainbow, orange too.
Yellow says, 'how do you do'.
Green is the next one, green for go.
Then comes blue and indigo.
Number seven, we must not forget, is pretty violet.

I must have learnt that song when I was five years old, yet I still use it on a regular basis to remember the colours. None of that 'Richard of York' rubbish for me.

A Song for the Elements, Anyone?

One Researcher asked the following:

Isn't there a song where all the elements of the periodic table are put to music? That sounds like quite a fun way of learning what is otherwise a very boring list of meaningless symbols.

Well, the answer is yes! The song's by Tom Leher and it's all about the elements. It's sung to the tune of 'A Modern Major General'.

There's antimony, arsenic, aluminium, selenium,
And hydrogen and oxygen and nitrogen and rhenium
And nickel, neodymium, neptunium, germanium,
And iron, americium, ruthenium, uranium,
Europium, zirconium, lutetium, vanadium
And lanthanum and osmium and astatine and radium
And gold, protactinium and indium and gallium (inhale)
And iodine and thorium and thulium and thallium.
There's yttrium, ytterbium, actinium, rubidium
And boron, gadolinium, niobium, iridium
And strontium and silicon and silver and samarium,
And bismuth, bromine, lithium, beryllium and barium.
There's holmium and helium and hafnium and erbium
And phosphorous and francium and fluorine and terbium
And manganese and mercury, molybdinum, magnesium,
Dysprosium and scandium and cerium and cesium
And lead, praseodymium, and platinum, plutonium,
Paladium, promethium, potassium, polonium, and
Tantalum, technetium, titanium, tellurium, (inhale)

Rhythm

I always remember how to spell the word 'Mississippi' by saying, almost singing, it in a very rhythmic way. If I didn't have the little rhythmic device, I wouldn't have a clue how to spell it. Anybody who's read Matilda by Roald Dahl should be able to spell 'difficulty':

Mrs D, Mrs I, Mrs FFI, Mrs CULTY

Again, this is said in a very rhythmic way, which makes it easy to remember.

Musical Pitch

There are two well-used mnemonics where music is concerned. For the uninitiated, music is written on staves (plural of staff) - one staff consists of five equally-spaced horizontal lines. The vertical position of a note in relation to these lines represents its intended pitch - notes can either be centred on a line, or in a space.

To remember the letter names of the notes on the lines, use the mnemonic 'Every good boy deserves football', as (from the bottom line of the staff to the top) the notes go E G B D F. For the notes in the spaces, you just have to remember FACE.

By the time you're playing notes on ledger lines (extra lines used to 'extend' the available range of pitch either above or below the staff) you should be able to recognise the 'staff notes' by sight.

Musical Key Signatures

Every piece of music is in a given 'key' - this basically defines which notes can be used in the music. But in every key except C major (and A minor) some of the notes will be a semitone higher or lower than normal - sharps are higher, flats are lower.

At the start of each line of music (although some pieces just have it on the first line) is the 'key signature'. This tells the player what notes are sharps or flats. However, there is a musically correct order to write the sharps/flats. So for sharp key signatures, remember: 'Father Charles Goes Down And Ends Battle', and for flat signatures: 'Battle Ends And Down Goes Charles' Father'.

The initial letters spell the order to write the sharps/flats. (Note that very few key signatures use 7 sharps/flats - in fact, there is no real reason to use more than 5).

Knuckle Months

There are many daft rhymes for remembering how many days here are in each month... but you might find knuckles easier. If you ball your fists and count off your knuckles from left to right, the knuckle bones (ie' the high bits) show you the 31 day months (with balled fists your thumb knuckle is out of sight and therefore isn't included). So, on the left you have JANUARY - february - MARCH - april - MAY - june - JULY - AUGUST - september - OCTOBER - november - DECEMBER (the final month being the third knuckle on your right hand). Well, heck, it helps some people.

And here's the old chestnut that most of us sing to remember the months of the year and the days each contain:

Thirty days hath September,
April, June and November,
All the rest have thirty-one
Excepting February clear
With twenty eight
Or twenty nine in each leap year

Stalactites and Stalagmites

To remember which is which: stalactites hold on tight and stalagmites grow up mighty. Or, stalactites have a 'C' and C is for 'ceiling'. Stalagmites have a 'G' and G is for 'ground'.

A slightly ruder version is, 'When the mites go up, the tights come down!'

Bottle Tops and Screws

Having trouble undoing a screw top, or something else similar? 'Lefty loosey, righty tighty' will remind you of the way to undo it. Unless you're in China - where it's all the other way round. According to one Researcher living in China, 'It takes me ages to unlock my door when I get home in the evening'.

Mind you, it's not necessarily as simple as it may at first seem:

If I recall correctly, the 'thread' on gas cannisters goes different ways round, depending on what is in the cannister. This means that you need two sorts of valves - one for left handed threads, one for right handed. Hopefully, this will ensure that (for instance) you don't mix up oxygen and carbon dioxide.

Right Hand Screw Rule

The right hand screw rule has two applications. Right, let's get technical! The first concerns vector geometry: given two vectors (directions with a given length), there is a third vector called the cross product, which is perpendicular (at right-angles) to both of the original vectors. But with just this information, the cross product could point in either of two directions - so which is it? This depends on the order you take the first two vectors - X x Y is opposite to Y x X.

The direction for X x Y is given by the right hand rule thus: hold your right hand straight, pointing in the X direction, palm on the left with your thumb at right angles to your fingers. Then curl your fingers until they point in the Y direction. This should only be possible in one direction (unless you are double jointed) - the direction of your thumb gives the direction of X x Y.

The second use is to determine the direction of a magnetic field, induced by an electric current. The use of the rule is slightly different depending on the setup - if the current occurs in a straight wire, imagine your right hand grasping the wire, with your thumb sticking out in the direction of current flow. Your fingers will then be pointing in the direction of the induced field. If the current occurs in a coil, half close your hand into a fist (again, with your thumb sticking out). Your fingers represent the coil, pointing in the direction of current flow. Your thumb will then (magically!) point in the direction of the magnetic field inside the coil.

Flemings Left And Right Hand Rules

If you place a wire with a current running though it in a magnetic field, it will move. The left hand rule can be used to remember which direction the resultant movement will be in: Spread your thumb, first and second fingers (on your left hand) so that they are all at right angles to each other. Then orient your hand so that your First finger points in the direction of the magnetic Field, and your seCond finger is in the direction of Current flow. Your THumb will then be pointing in the direction of THrust. (eg - magnetic field flowing away from your body, forwards, current flow is left to right, resulting in thrust upwards)

If you move a wire in a magnetic field, a current is generated. The right hand rule can be used to remember the direction of current flow: again spread thumb, first and second fingers. Point your THumb in the direction of THrust, and First finger in the direction of the magnetic Field. Your seCond finger then points in the direction of the resulting Current. (eg magnetic field is forwards, away from you, thrust is vertically upwards, resulting in current flowing from right to left).

Mathematics

To remember the digits of Pi (3.14159):

How I wish I could calculate Pi.

The number of letters in each word gives the digits in Pi.

How I want a drink, alcoholic of course after all those chapters involving Quantum Mechanics.

Arithmetic

Written mathematics can be a little confusing. Especially when it's written sloppily. For instance, which of the following is correct?

Which order should you do the subtraction and multiplication? Common sense would probably tell you to perform the operations in the order that they appear - ie, left to right. Unfortunately, this would give the wrong answer for this example! In fact, the operations should be performed:

Brackets, Indices, Division, Multiplication, Addition, Subtraction.

Remember this order with BIDMAS.

So our example should be computed as:

Classification of Man

In high school, we were assigned the task in Biology of memorising (BSp, memorising) the scientific classification of man. The acronym mnemonic that this Researcher created must have worked, because he has remembered the classification for over 30 years now! It's somewhat silly, but that probably makes it work better.

King Arthur picked cherries so Vicky could make one pie for his German helper, Sally Schwann

The classification is as follows:
Kingdom - Animal
Phylum - Cordata
SubPhylum - Vertebrata
Class - Mammalia
Order - Primates
Family - Hominidae
Genus - Homo
Species - Sapien

Ways to Remember Stuff... Besides Tying a String to Your Finger

I've never used mnemonic codes to remember facts. I find the best way to remember something is to repeat it in more than one form of communication. For instance, I want to remember that metamorphic rock is created by heat and pressure from sedimentary rock. So I write it down in class. Then while studying later, I say it out loud. This way I remember it two ways - once spoken, once written. It's also better in the long run, because while you may still remember the code five years from now, what's the chance that you'll know what the letters stand for?

And taking this idea further...

I think you stand a greater chance of remembering things if you're more 'interactive' with them. In order of increasing 'memorability': Hear it, see it, say it, do it. If you're just listening to a lecture, it can be very difficult to remember anything other that the basic concepts. If you see a demonstration, this should reinforce the ideas. Saying things out loud helps because it (should be) making you think about what you're saying. Actually doing something connected with it (eg, repeated calculations using a particular method) will help you remember not just the concepts, but also the actual processes.

Monarchs

Here's one for the monarchs of Britain.

Willie Willie Harry Stee
Harry Dick John Harry three;
One two three Neds, Richard two
Harrys four five six....then who?
Edwards four five, Dick the bad,
Harrys (twain), Ned six (the lad);
Mary, Bessie, James you ken,
Then Charlie, Charlie, James
again...

Will and Mary, Anna Gloria,
Georges four, Will four, Victoria;
Edward seven next, and then
Came George the fifth in nineteen
ten;
Ned the eighth soon abdicated
Then George six was coronated;
After which Elizabeth
And that's all folks until her
death.

And to remember the fate of Henry VIII's wives...

Divorced, Beheaded, Died, Divorced, Beheaded, Survived

How Not To Recall Facts

A word of warning...

I did a psychology degree and we were taught that people recalled facts better in the same 'state' that they memorised them. They found that people sitting on the bottom of a swimming pool recalled more successfully the facts they had memorised sitting at the bottom of the pool rather than ones they had memorised elsewhere. Because I was usually boozing whilst revising, I decided that getting pissed before my exam would mean I would recall things better. It didn't, I failed.

The Dirtier the Better

Two very rude examples of mnemonics for the purpose of recalling anatomy! The first, branches of the facial nerve:Temporal, Zygomatic, Buccal, Mandibular and Cervical. Now, these are typically unmemorable - or at least, their real names are. The mnemonic, however, is hard to forget:

Two Zulus b****red my cat

The ascending order of the branches of the external carotid artery are again, typically, hard-to-remember names: Ascending Pharengeal, Superior Thyroid, Lingual, Facial, Occipital, Posterior, Auricular, Superior Temporal and Maxillary. These names you might forget; the mnemonic, however, you won't:

As Sally lay flat, Oliver's penis sprayed magnificently!

Actually, anatomy being the variable beast that it is, the first two branches can be found to be swapped around, so a new mnemonic can be formed thus: 'Sally's anus loudly farted; Oliver's penis sprayed magnificently!

The Cranial Nerves supplying the muscles that move the eye: the Cranial Nerves III, IV and VI all supply the muscles which move the eye - if a nerve, or several, are damaged, it will cause very specific paralysis of the muscle, and hence, maybe you might not be able to move you eye from left to right, and so on. The memory device is:

SO4, LR6 and all the rest are 3

This translates as: Superior oblique is controlled by cranial nerve IV, lateral rectus, which turns your eye to look out, is controlled by cranial nerve VI, and all the other recti (rectangular muscles) are controlled my cranial nerve III.

Titter Ye Not - We're Getting Ruder!

Oh, Oh, Oh To Touch and Feel Very Good Virgins And Homosexuals

Oh dear. Or for the rotator cuff (shoulder muscles) Teres minor, Infraspinatus, Supraspinatus, Subscapular, you can have:

Tarts In Silk Stockings

Remembering all this rubbish was just one of the reasons I gave up medicine And, before anyone asks: yes, I could remember the mnemonics; no, I couldn't remember what they stood for and had to look them up...

The Great Lakes

One Researcher could never remember the names of the Great Lakes, until her fifth grade teacher taught her 'HOMES'.

H for Lake Huron
O for Lake Ontario
M for Lake Michigan
E for Lake Erie
S for Lake Superior

Counties of Northern Ireland

For remembering the counties of Northern Ireland (Down, Tyrone, Londonderry, Antrim, Armagh, Fermanagh) just utter the following magic mnemonic:

Don't Take Long Add Another Fossil

The Spectrum

Richard Of York Gave Battle In Vain

'Richard of York gave battle in vain' is all very well but if you want to impress the spectrum in reverse is remembered as 'Virgins in bed get your organs ready' see; violet, indigo, blue, green, yellow, orange and red.

There's always one, isn't there?

Chocolate Eclairs

My fave mnemonic was given to my 1st year English class by the lovely Mr Smith, and serves the important function of helping all 11-year-olds to spell the word 'necessary' correctly every time, which let's face it is unspeakably crucial to all those teetering on the brink of adolescence. It goes like this: Never Eat Chocolate Eclairs Since Some Are Rather Yucky. Unfortunately (and I have carried out extensive research on this matter) it is based on a completely false premise. But I've never forgotten it! Never Eat Shredded Wheat is also useful for remembering the points of a compass in clockwise order. I don't know any that aren't about food, sorry.

Is this Necessary... Again?

Spelling 'necessary' was terribly difficult for me, until I was told (in my 20s!) that it's one coat, and two shoes. One c and two ss.

Geology

This one's strictly for the geologists among you: it's a mnemonic for the Geological Time Periods:

Pink = Precambrian
Camels = Cambrian
Often = Ordovician
Sit = Silurian
Down = Devonian
Carefully = Carboniferous
Perhaps = Permian
Their = Triassic
Joints = Jurassic
Creak = Cretaceous
Painfully = Paleocene
Early = Eocene
Oiling = Oligocene
Might = Miocene
Possibly = Pliocene
Prevent = Pleistocene
Rheumatism = Recent

Biology

Ever have to remember the order of the different categories in taxonomy? Well, one of our Researchers did. The order is: Kingdom, Phylum, Class, Order, Family, Genus and Species. Your wonderful sentence to help you is:

King Philip came over for good soup

Scandinavian Flatulence

We're getting rude again...

As a geography-impaired individual (ie, American), I struggled mightily through high school freshman year World History class to memorize the map of Europe. For some reason, I had particular trouble remembering the order of the northern peninsular countries...until I developed this handy (albeit juvenile) mnemonic device. From West to East; Norway, Sweden, Finland. 'No Smelly Farts'.

Synaesthesia

For people with Synaesthesia mnemonics are often spurious, as their own neurology helps them to recall things vividly and accurately. Look hard at yourself, to see if you do have any synaesthesic tendencies, and practice them to maximise them! Even if you are not a true synaesthete, it's possible to get a reasonably effective artificial synaesthesia going, especially for the short term, like revising for an exam. Make the most of your best sense: if you're visual, use diagrams, if your auditory, use songs. It's no good trying your room-mate's failsafe revision technique if you're brains are wired differently!

Making a Good Impression

A way I used to revise was to do impressions of teachers or tutors. I'd practise these impressions to make my friends laugh, but I found I was also able to remember the way the teacher pronounced certain words and it helped me to recall whole chains of information. I came top of the class in chemistry one year because we had a teacher with a very distinctive voice, whereas the following year I came absolute bottom because the teacher was so non-descript.

And of course, the Memory Palace - an idea that appears in the book 'Hannibal' - where you construct a mental image of your dream home and then fill each room with all the things you need to remember. For example, in your 'study', you might have a table where you keep your bills, and because you mentally store each one face up, you can then use it to remember which bill is due next. You might have a birthday room, where you celebrate people's birthdays, and all around the room are photos of your friends in the order of their birthdays.

In the 'kitchen', you might lay out all the ingredients to a complicated recipe so you can then remember them - and the order they come into use - as you work just by bringing forward the mental picture.

It takes time to perfect, but it can come in handy if you have to remember things like a shopping list. You can picture your Memory Palace and place all the items you need to remember on the floor along your route from, say, the bedroom to the kitchen, or one in each of the rooms you come to if you mentally 'walk' around the upper landing in a clockwise direction...

Police Codes and Signals

Most police agencies use codes on the radio and when speaking to each other. It allows policeman and women to communicate a lot of information quickly. It can also be used to be somewhat covert.

If I'm on a scene with another officer, and I want to tell him that the person is a drug user, I can say, '38D' and he knows what I mean. Many people who have frequent contact with the police often learn some of the signals too. So it isn't a completely secure means of communicating.

Some of these codes come into the modern vernacular. In Los Angeles, the police use penal code numbers as their codes. If you've ever seen an episode of '1-Adam-12', you've heard them respond to a 411 in the opening credits. PC 411 of the California penal code defines Armed Robbery. California penal codes have entered into gang vernacular and the use of California PC codes is used nationwide by gang members in graffiti. One predominant one is 187, which means murder.

My agency, along with many of the other agencies around Atlanta use 99 signals going in between 1 and 99. So if I want to remember a number, I can remember it as a series of events. The other day, I was looking at a van I want to buy. I didn't have a pen to write down the phone number of the owner. The prefix for the number was a common one that was easy to remember. The last four were 0529. That breaks down to 'spouse' (Signal 5) and 'fight' (Signal 29). So I remember it as 'a fight with my wife.'