Fibonacci was born during a time of pivotal transition. Europe was emerging from the Dark Ages and the states in Italy were on the leading edge. They were prospering from trade in the Mediterranean. They were held back, however, by the Roman numeral system which made calculations cumbersome. This was about to change.
As Fibonacci described in the introduction to his first book, Liber Abaci:
After my father's appointment by his homeland as state official in the customs house of Bugia for the Pisan merchants who thronged to it, he took charge; and in view of its future usefulness and convenience, had me in my boyhood come to him and there wanted me to devote myself to and be instructed in the study of calculation for some days. There, following my introduction, as a consequence of marvelous instruction in the art, to the nine digits of the Hindus, the knowledge of the art very much appealed to me before all others, and for it I realized that all its aspects were studied in Egypt, Syria, Greece, Sicily, and Provence, with their varying methods; and at these places thereafter, while on business. I pursued my study in depth and learned the give-and-take of disputation. But all this even, and the algorism, as well as the art of Pythagoras I considered as almost a mistake in respect to the method of the Hindus. Therefore, embracing more stringently that method of the Hindus, and taking stricter pains in its study, while adding certain things from my own understanding and inserting also certain things from the niceties of Euclid's geometric art. I have striven to compose this book in its entirety as understandably as I could, dividing it into fifteen chapters. Almost everything which I have introduced I have displayed with exact proof, in order that those further seeking this knowledge, with its pre-eminent method, might be instructed, and further, in order that the Latin people might not be discovered to be without it, as they have been up to now. If I have perchance omitted anything more or less proper or necessary, I beg indulgence, since there is no one who is blameless and utterly provident in all things.
Fibonacci recognized the superiority of the Indian numbering system (which we use today) for use in calculating and business. He learned while abroad in North Africa (called the Barbary Coast) and brought this back to Europe. It was well-received and, gradually, the use of 1 to 9 replaced the Roman I to IX. By making arithmetic easier, more people could do it successfully.
