Science · 628 CE
Zero becomes a number
Bhinmal (Bhillamala), Rajasthan (India)
Indian mathematicians had been writing numbers with base-10 place value for centuries (the earliest leaves of the Bakhshali manuscript are dated to about 224–383 CE), and around 500 Aryabhata marked empty places with the word kha, 'emptiness'. In 628 Brahmagupta, a native of Bhillamala, completed his Brahmasphutasiddhanta, the earliest known text to treat zero as a number in its own right, with rules for adding, subtracting and multiplying with zero and negative numbers.
Why it mattered
Translated into Arabic at the Abbasid court, spread by al-Khwarizmi's book on Hindu numerals (c. 825) and brought into Europe from the 12th century, Indian place-value numerals with zero became the digits the whole world uses today.
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