Numbers

Pi

The Greek letter π (transliterated into English as pi) is used to denote one of the most famous constants in mathematics: the ratio between the diameter and circumference of a circle. It's what's known as an irrational number, because it can't be expressed as a ratio (i.e. a fraction). For this reason, it is impossible to give an exact value for pi; all we can do is give an approximation.

At school we were taught (or we were in my day) that the fraction 22/7, or three and one seventh, gives a close approximation to pi. This is a rational number, because it can be expressed as a ratio, but like pi it can't be written down exactly as a decimal fraction, because its digits repeat (or recur, as the mathematicians say) ad infinitum. It's equal to approximately 3.142857; after this, those six digits (the ones after the decimal place) recur.

The actual value of pi, to 31 decimal places, is 3.1415926535897932384626433832795.

It's always useful to know the first few digits of pi, but unless you're a memory expert (in a way that a quizzer isn't necessarily) you'll probably need a mnemonic.

There are various mnemonics, and most if not all of them involve learning a sentence or verse where the number of letters in each word in turn gives you the requisite digits.

Here's one I learnt from BBC Radio 4's Brain of Britain, some years ago, which gives the first eight digits (including the one before the decimal point):

This has always been enough for me in any quiz where the subject (of the value of pi) has ever come up.

Mathematicians will notice that it's not strictly correct, because if we were giving the value of pi to eight significant figures, or seven decimal places, the eighth digit should be a 7 and not a 6.

If you'd like to see a mnemonic for more digits of pi, I would refer you to i before e (except after c), by Judy Parkinson (Michael O'Mara Books Ltd, London, 2007). Subtitled Old–School Ways to Remember Stuff, this book is all about mnemonics, and it gives various examples for pi – including one that gives you the 31 digits as above. It stops at 31 because (as Ms. Parkinson herself points out) the 32nd decimal place is occupied by a zero, which can't easily be covered by the method of counting the number of letters in words.

You will also find several other mnemonics in Ms. Parkinson's book which I've stolen for this website.

Short–Lived Appointments (Number of Days)

John Paul I as Pope (1978)		33
Steve Coppell as manager of Manchester City (1996)		33
Brian Clough as manager of Leeds United (1974)		44
Liz Truss as UK Prime Minister (2022)		49
Sam Allardyce as England manager		67

Other

The questions in this section have nothing in common, except that in each case, the answer is a number.

Where a number is followed by an ellipsis (...), this means that the value given here is approximate.

Square root of 0.25		0.5
Surfaces on a Mobius strip		1
Square root of 2		1.414...
The 'golden ratio' (known to mathematicians as phi)		1.618...
The only even prime number; also the lowest (1 no longer qualifies)		2
The base of natural logarithms (e) – a.k.a. Euler's number or Napier's constant		2.71828184...
Hearts of an octopus		3
Spots on the Domino's Pizza logo
Pi (see previous section for more)		3.1415926535878...
Compartments in the stomach of a cow		4
Horses involved in the bet known as a Yankee
Lines in a clerihew
Arms of a starfish		5
Halogens (naturally occurring)
Lines in a limerick
Sides of a prism
Lines on the stave, in music
Number of places (in each of which there may or may not be a dot) in the cell, or grid, used to represent a character in Braille		6
Pips in the Greenwich Time Signal (the last one is a long one)
Points on a snowflake
Points on the Star of David
Wings of a Seraph
Hills of Rome (and of Jerusalem, Lisbon and Sheffield, among many others allegedly)		7
Opposite sides of a die add up to
Emirates in the United Arab Emirates
Points on the Statue of Liberty's crown
Sides on a 50p piece
Neutral on the pH scale		7.0
Bits in a byte (always, in quizzes!)		8
Corners on a cube
Humans (traditionally) on Noah's Ark
Nails in a horseshoe (normally)
Points on a Maltese Cross
Records allowed on Desert Island Discs
Queen Victoria's children		9
Gates in the Thames Flood Barrier		10
Legs on a lobster
Limbs on a squid (the majority of which can be called arms)
Herbs & spices used in KFC's secret recipe		11
Confederate states
Branches on the antlers of a male stag (minimum)		12
Labours of Hercules
Tribes of Israel
Avenues that radiate from the Place Charles de Gaulle (Paris – previously, and sometimes still, known as the Place de l'Etoile)
Baker's dozen		13
People at the Last Supper
US colonies (states) that declared independence in 1776, and hence stripes on the US flag
Witches in a coven
Enigma variations (Elgar)		14
Lines in a sonnet
Stations of the Cross
Degrees of longitude in a time zone		15
People on a jury, in Scotland
Stones per player at the start of a game of Backgammon
National republics in the Soviet Union, and the number of independent republics that it was divided up into in 1991
Annas in a rupee		16
Syllables in a haiku		17
Quires in a ream		20
Shillings in a guinea (prior to 1971)		21
Spots on a die
Letters (characters) in the Hebrew alphabet		22
Pairs of chromosomes in each human cell		23
Letters in the Greek alphabet		24
Pieces at the start of a game of draughts
Sheets in a quire		25 (or 24)
Counties in the Republic of Ireland		26
Cantons in Switzerland
Amendments (to date) to the US Constitution		27
EU member states (the latest to join was Croatia in 2013)		28
Characters in the Arabian alphabet
Pieces in a set of dominoes
The Chatanooga Choo Choo left on track number		29
Pieces in a chess set		32
Points of the compass
Boroughs in Greater London (not counting the City of London)
Pods on the London Eye
Letters in the Russian alphabet (including two "modifier letters", or "signs", which alter the pronunciation of a preceding consonant and/or a following vowel)		33
Numbers on a roulette wheel (European – including French and British)		37 (0–36)
Numbers on a roulette wheel (American)		38 (0–36, plus 00)
Lewis Hamilton's racing number, in Formula 1		44
Strings on a harp		46 or 47
Original members (1945) of the United Nations		50
Countries in the Commonwealth		53
Small squares on a Rubik cube		54 (6 x 9)
Letters in Llanfairpwllgwyngyllgogeryllwyndrobwyllllantisiliogogogoch		58
'The Brighton Line' (in what Bob Monkhouse used to call "Bingo lingo")		59
Squares on a chess (or draughts) board		64
Joe Root's squad number in limited overs internationals		66
Cards in a Tarot pack		78
Small squares (into each of which you write a number) on a Su Doku grid		81
Keys on a standard piano		88
Speed, in mph, that the DeLorean had to reach in order to travel through time (in the Back to the Future franchise)
The highest number in bingo (standard version)		90
Theses in Martin Luther's Disputation on the Power and Efficacy of Indulgences (1517)		95
Room that contains "the worst thing in the world" (i.e. whatever the victim is most afraid of) in George Orwell's Nineteen Eighty–Four		101
Floors in the Empire State Building		102
A supercentenarian is someone who is over ... years old		110
Emergency phone number, in the EU and several other countries – standardised by the EU Council in 1991, reaffirmed in 2002		112
Number of years that the Hundred Years War lasted for		116 (1337–1453)
Elements in the Periodic Table (the last four being officially named in 2016)		118
Number you would dial to get the Speaking Clock on most major UK networks (standardised in the early 1990s)		123
Tiles in Mah Jongg (Western version)		144
Hours in a week		168 (24 x 7)
Spots on a set of (double six) dominoes		168 (21 x 8)
Number for the UK's Directory Enquiries service, operated exclusively by British Telecom until 2002		192
Pennies in a pound (pre–1971)		240
Squares on a Scrabble board		225 (15 x 15)
Sheets in a ream		500
Total of all the numbers on a roulette wheel		666
Arabian Nights		1,001
Bytes in a kilobyte		1,024 (210)
Bytes in a megabyte		1,048,576 (220)

© Haydn Thompson 2017–24