The Hindu-Arabic Numerals c5.20

c5.20

Probably the most striking testimony from Arabic sources is that given by the Arabic traveler and scholar Moḥammed ibn Aḥmed, Abū 'l-Rīḥān al-Bīrūnī (973–1048), who spent many years in Hindustan. He wrote a large work on India,³ one on ancient chronology,⁴ the "Book of the Ciphers," unfortunately lost, which treated doubtless of the Hindu art of calculating, and was the author of numerous other works. Al-Bīrūnī was a man of unusual attainments, being versed in Arabic, Persian, Sanskrit, Hebrew, and Syriac, as well as in astronomy, chronology, and mathematics. In his work on India he gives detailed information concerning the language and customs of the people of that country, and states explicitly¹ that the Hindus of his time did not use the letters of their alphabet for numerical notation, as the Arabs did. He also states that the numeral signs called *aṅka*² had different shapes in various parts of India, as was the case with the letters. In his *Chronology of Ancient Nations* he gives the sum of a geometric progression and shows how, in order to avoid any possibility of error, the number may be expressed in three different systems: with Indian symbols, in sexagesimal notation, and by an alphabet system which will be touched upon later. He also speaks³ of "179, 876, 755, expressed in Indian ciphers," thus again attributing these forms to Hindu sources.