Fibonacci was interested in the arabic numbers and wrote a book called "The Book Of Calculations" which was basically a showcase of the arabic numbers. However, many people didn't want to use the new numbers. People in Italy had different currencies in most of the cities and you had to change currencies if you went to visit another city. To exchange the money, you had to go to a money exchange bench or bank. Some of the people who exchanged the currencies used the old system which was using an abacus but instead of beads, you used counters in which you could see what the exchanger was doing but the other people used the new Indian numbers. People couldn't understand what the Indian numbers were so they couldn't check if the exchanger was cheating them or not. Soon, some cities in Italy banned using the new numerals. For example, in 1299 BC, the city of Florence banned the use of the new numerals.