Arabic numerals
The first mentions of the numerals in the West are found in the "Codex Vigilanus" of 976.
History of combinatorics
Combinatorics came to Europe in the 13th century through mathematicians Leonardo Fibonacci and Jordanus de Nemore. Fibonacci's Liber Abaci introduced many of the Arabian and Indian ideas to Europe, including that of the Fibonacci numbers. Jordanus was the first person to arrange the binomial coefficients in a triangle, as he did in proposition 70 of "De Arithmetica". This was also done in the Middle East in 1265, and China around 1300. Today, this triangle is known as Pascal's triangle.