Arabic numerals

Arabic numerals, also called Hindu–Arabic numerals, are the ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. The term often implies a decimal number written using these digits, which is the most common system for the symbolic representation of numbers in the world today. However the term can mean the digits themselves, such as in the statement 'octal numbers are written using Arabic numerals.' The Hindu–Arabic numeral system (i.e. decimal) was developed by Indian mathematicians around AD 500. From India, the system was adopted by Arabic mathematicians in Baghdad and passed on to the Arabs farther west. The Arabic numerals developed in North Africa. It was in the North African city of Bejaia that the Italian scholar Fibonacci first encountered the numerals; his work was crucial in making them known throughout Europe. European trade, books, and colonialism helped popularize the adoption of Arabic numerals around the world. The term Arabic numerals is ambiguous, it may also be intended to mean the numerals used by Arabs, in which case it generally refers to the Eastern Arabic numerals. Although the phrase 'Arabic numeral' is frequently capitalized, it is sometimes written in lower case: for instance in its entry in the Oxford English Dictionary, which helps to distinguish it from 'Arabic numerals' as the Eastern Arabic numerals. Other alternative names are Western Arabic numerals, Western numerals, Hindu numerals, and Unicode calls them digits. The decimal Hindu–Arabic numeral system with zero was developed in India by around AD 700. The development was gradual, spanning several centuries, but the decisive step was probably provided by Brahmagupta's formulation of zero as a number in AD 628. Prior to Brahmagupta, zero was in use various forms but was regarded as a 'blank spot' (sunya sthana) in a positional number. It was only used by mathematicians (ganakas—people doing calculations) while the general populace used the traditional Brahmi numerals. After 700 AD, the decimal numbers with zero replaced the Brahmi numerals. The system was revolutionary by limiting the number of individual digits to ten. It is considered an important milestone in the development of mathematics. The numeral system came to be known to the court of Baghdad, where mathematicians such as the Persian Al-Khwarizmi, whose book On the Calculation with Hindu Numerals was written about 825 in Arabic, and the Arab mathematician Al-Kindi, who wrote four volumes, On the Use of the Indian Numerals (Ketab fi Isti'mal al-'Adad al-Hindi) about 830, propagated it in the Arab world. Their work was principally responsible for the diffusion of the Indian system of numeration in the Middle East and the West. In the 10th century, Middle-Eastern mathematicians extended the decimal numeral system to include fractions, as recorded in a treatise by Syrian mathematician Abu'l-Hasan al-Uqlidisi in 952–953. The decimal point notation was introduced by Sind ibn Ali, who also wrote the earliest treatise on Arabic numerals. According to Al-Beruni, there were multiple forms of numerals in use in India, and 'Arabs chose among them what appeared to them most useful'. Al-Nasawi wrote in the early eleventh century that the mathematicians had not agreed on the form of numerals, but most of them had agreed to train themselves with the forms now known as Eastern Arabic numerals. The oldest specimens of the written numerals available from Egypt in 260 A.H. (873–874 CE) show three forms of the numeral '2' and two forms of the numeral '3', and these variations indicate the divergence between what later became known as the Eastern Arabic numerals and the (Western) Arabic numerals.