"Dodgson was fond of children, of Tuesdays, and of the number 42"

Martin Gardner (mathematician), "The Universe in a Handkerchief".

The
legend says that, after having enjoyed "Alice in Wonderland",
Queen Victoria asked Lewis Carroll to send her a copy of his next
book. She received "An elementary treatise on Determinants"
shortly afterwards. This story was never confirmed neither denied,
but oh how much we wish it was true, and that we also could see the
Queen's face!

We
all know (and love!) "Alice in Wonderland", and we all
might have as well read something on the maths in the book. But some
of you might not know that Charles Dodgson (the real name of Lewis
Carroll) was also a "serious" mathematician who lectured at
Oxford and even had his say on tennis tournaments until mid-20th
century.

He
was the third of eleven children and, from a young age, he started
showing a talent for writing as well as for mathematics, and he would
create stories and puzzles for his siblings, often involving fantasy
and numbers. He went to Oxford to study mathematics and, being the
top student was the start of a very long and succesful career in
mathematical research as well as in teaching.

One
of his most popular achievements as a mathematician came from the
fact that he found unfair the way tennis tournaments were organised
at that time, so he designed a fairer method to ensure that the most
skilled players would pass to the latest rounds; this method was in
use until 1942. The national election in 1880, along with the
election of an architect for works at the University of Oxford as
well as the criteria for the selection of university lecturers, led
him to write on the limitations on the traditional election methods
merely based on majority, and on how to improve them with a system by
which every voter could not only vote for their favourite candidate
but also for a number of their preferred alternatives.

He
also published mnenotechnical rules to remember dates and numbers, a
method for writing encrypted messages, and an algorithm to find
out the date of every Easter Sunday until 2499. He could
remember the first 71 digits of pi by using a series of nonsense
rhymes, and he also applied this system for memorising the logarithms
of every prime number under 100.

His
pseudonym was invented when the editor of a magazine for which
Dodgson wrote stories and puzzles, thought he should distinguish his
entertainment works from his academic publications. Charles proposed
a few names, and we should thank the editor for rejecting Edgar UC
Westhill and selecting Lewis Carroll instead! Carroll's
contributions to literature were very influenced by maths, paradox
and logic.

His
fascination with the number 42 is patent in the following facts:

-Alice's
Adventures in Wonderland has 42 illustrations.

-The
King reads Rule Forty-two in Alice's Adventures in Wonderland: "All
persons more than a mile high to leave the court". That,
despite not being the number one, is the most important rule, and it
becomes a problem for Alice when she eats some mushrooms.

-In
the preface to "The Hunting of the Snark", he also mentions a rule 42
as the most important of them all. Later, in the same book, he says
the baker had "forty-two boxes, with his name painted clearly on
each."

-In
his poem Phantasmagoria, he talks about chasing a 42 year old man.

His
ability for teaching is easily seen in his guides for students and in his
more than 10000 letters to children. Every child he knew would
receive a riddle at some point. Many of them required the application
of mathematics, but some needed only patience and common sense as
they were simply based on a pun or on memory. He used to find humour
in the dullest subjects and never underestimated children; he in fact
wrote that

*intelligence seemed to vary inversely with size*. His popular stories include horror tales, plays, riddles, and poems that, beyond the mathematical questions, also show the absurdity and lack of common sense when logic is applied.
Once
he even proved that 2 x 2 = 5, and challenged his readers to find
what was wrong in his deduction:

Honoured Sir,

Understanding you to be a distinguished algebraist (i.e. distinguished from other algebraists by different face, different height, etc.), I beg to submit to you a difficulty which distresses me much.

If x and y are each equal to ‘1,’ it is plain that 2 × (x^{2}– y^{2}) = 0, and also that 5 × (x – y) = 0.

Hence 2 × (x^{2}– y^{2}) = 5 × (x – y).

Now divide each side of this equation by (x – y).

Then 2 × (x + y) = 5.

But (x + y) = (1 + 1), i.e. = 2.

So that 2 × 2 = 5.

Ever since this painful fact has been forced upon me, I have not slept more than 8 hours a night, and have not been able to eat more than 3 meals a day.

I trust you will pity me and will kindly explain the difficulty to

Your obliged, Lewis Carroll

________________

Martin
Gardner was a fantastic mathematician, a great fan of Lewis Carroll,
and the responsible for the best "Alice in Wonderland"
edition so far:

*"The Annotated Alice".*
Charles
Dodgson's contributions as a mathematician.

A
marvellous book.

And if you cannot stop wondering about how come two two times is five, here you go this.

And if you cannot stop wondering about how come two two times is five, here you go this.

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