In the book "The Man of Numbers," Keith Devlin describes how Fibonacci (yes, the Fibonacci, a nickname) introduced Hindu-Arabic numerals as well as double-entry bookkeeping to the West in 1202. He wrote an encyclopedia of arithmetic that included the now-famous Fibonacci sequence, though that sequence was not a major contribution to math at the time.

hi! /u/Jooseman gave a good overview a few weeks ago

• When and how did Arabic numbers get adopted worldwide?

and here are some earlier posts that may be of interest

• When and how did Asian countries switch to the use of Arabic numerals?

• How and when did the arabic numbers took over the roman numbering system in Europe?

• Why did Arabian numerals become the dominant numerals in Europe over Roman numerals?

• When did Roman numerals stop being used?

• At what point did it seem Western culture switched from "Roman" numerals (I,V,X,etc.) to the more modern, "Arabic-Hindu" numerals (1,2,3,etc.)?

• How did the Arabic numerals become the world standard, essentially, for enumeration?

• What kind of counting systems did they use in Europe before Arabic numerals became widespread?