Arabic numerals
The first mentions of the numerals in the West are found in the "Codex Vigilanus" of 976.
Lupitus of Barcelona
Lupitus was instrumental in the transfer of Arabic mathematics, including the astrolabe and the Hindu-Arabic numeral system to Christian Europe. Gerbert of Aurillac in a letter of 984 asks Lupitus for a translation of an Arabic astronomical treatise, the "Sententiae astrolabii".