ARABIC NUMERALS. — The system currently in use for denoting numbers, known as Arabic numerals, actually originated with the Indians and, according to the most common theory, is composed of the initial letters of each numeral’s name in Sanskrit. Knowledge of this system, however, reached Europe through the Arabs, who had been familiar with it since the 8th century.
The treatise by Abū Gā’far Muḥammad b. Mūsā al-Ḥwarizmī, composed during the caliphate of al-Ma’mūn (813–33), survives in a Latin translation. The earliest mention in Latin manuscripts appears in two Spanish codices of Isidore’s *Etymologiae seu Origines*: one from 976, originating from the monastery of Albelda (Escorial codex d. I, 2), and another from 992, written at San Millán de la Cogolla (Escorial codex d. I, 1). At the beginning of Book III, a gloss attributes the use of Arabic numerals to the Indians and lists the numerals in reverse order, from 9 to 1 (excluding zero), a circumstance sufficient to demonstrate that they had not yet been applied within the decimal system.
From Spain, the knowledge of Arabic numerals spread to France, England, Germany, and subsequently to Italy,
not without opposition; in 1299, the statutes of the Florentine money-changers’ guild required that numbers be written in full to prevent easy falsification. Yet by 1202, Leonardo Fibonacci’s *Liber abaci* (filius Bonacci) of Pisa—who had learned the system in the Pisan colonies of North Africa—had already demonstrated its practicality, popularizing the use of the four arithmetic operations. From the 15th century onward, Arabic numerals entered general use and, with minor exceptions for 3 and 4, appear in the same form across all countries.