Arabic numerals
The first mentions of the numerals in the West are found in the "Codex Vigilanus" of 976.
Arabic maqam
Since microtonal intervals are impractical to accurately notate, a simplified musical notation system was adopted in Arabic music at the turn of the 20th century. Starting with a chromatic scale, the Arabic scale is divided into 24 equal quarter tones, where a quarter tone equals half a semitone in a 12 tone equal-tempered scale. In this notation system all notes in a "maqam" scale are rounded to the nearest quarter tone.