Leonardo Fibonacci was born around 1170 in Pisa. His father was an agent for Pisan merchands in the north of Africa. Leonardo gets a decent education.[br]While in Europa one still uses Roman numbers, the Arabs already had adapted a number system with placevalues. And from childhood the young Leonardo was skilled in calculating.

Fibonacci loved trivial counting problems, the kind you can find all over.[br]But one of them made his name immortal:[br][br][i] "A man put a pair of rabbits in a walled space.[br]  After a month a pair of rabbits is sexually mature and every month it gives birth to a new pair.[br]  How many pairs doe you get after a year?"[br][/i](PS: this is just a mathematical assumption, not a real biological description of reality)[br][br]These numbers form the sequence of Fibonacci.[br]Here's the pedigree for the first months: