# The twenty-third of February, 2011: Lonely and Chalk

A nice coincidence, this. I knew (I think) what Fibonacci numbers were – they’re numbers in a sequence that begins with two positive integers and in which subsequent numbers are the sum of the proceeding two (like 2, 3, 5, 8, 13…). On reading The Man Who Loved Only Numbers this morning, I learned that Fibonacci numbers were first investigated by Francois Édouard Anatole Lucas (1842-1891) around 600 years after the death of Leonardo Fibonacci (about 1170 – 1240, or thereabouts)  – and that the origin of the sequence is to be found in the following silly puzzle (set by Fibonacci).

A certain man put a pair of rabbits in a place surrounded by a wall. How many pairs of rabbits can be produced from that pair in a year if it is supposed that every month each pair begets a new pair which from the second month on becomes productive?

The answer – of course! – is 377. The tirelessly multiplying rabbits number first 1 pair, then 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, and 377 pairs. This was the prototype Fibonacci sequence.

I was delighted, later today, to come across a gallery of work by the children’s writer and illustrator Emily Gravett. This led me to Gravett’s book The Rabbit Problem:

How does 1+1 = 288? A family of rabbits soon provides the answer! Hop along to Fibonacci Field and follow Lonely and Chalk Rabbit through a calendar year as they tackle a variety of seasonal challenges and cope with their fast expanding brood.

This is a book that I think ought to be issued to all children at birth, or at least on the occasion of their first pair of glasses (I don’t wear glasses, and never have, which I suspect explains why I’m not all that good at maths). Here are Ms Gravett’s mathematically correct rabbits.

And here’s a link to the lovely books blog Seven Impossible Things Before Breakfast, from which I filched this picture.