Quiz Monkey |

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):

May I have a large container of coffee? |

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.

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

© Haydn Thompson 2017–19