Arabic numerals
The first mentions of the numerals in the West are found in the "Codex Vigilanus" of 976.
History of the Arabic alphabet
The alphabet then had 28 letters, and so could be used to write the numbers 1 to 10, then 20 to 100, then 200 to 900, then 1000 (see Abjad numerals). In this numerical order, the new letters were put at the end of the alphabet. This produced this order: alif (1), b (2), j (3), d (4), h (5), w (6), z (7), H (8), T (9), y (10), k (20), l (30), m (40), n (50), s (60), ayn (70), f (80), S (90), q (100), r (200), sh (300), t (400), th (500), dh (600), kh (700), D (800), Z (900), gh (1000).