The Fibonacci Series
In Fibonacci's book he introduces a problem for his readers to use to practice their arithmetic:-
a pair of rabbits are put in a field and, if rabbits take a month to become mature and then produce a new pair every month after that, how many pairs will there be in twelve months time?
He assumes the rabbits do not escape and none die. The answer involves the series of numbers:
1, 1, 2, 3, 5, 8, 13, 21, ...
but it was the French mathematician Edouard Lucas (1842-1891) who gave the name Fibonacci numbers to this series and found many other important applications of them.