In 628 AD the Indian mathematician and astronomer Brahmagupta, working at Bhillamala in Rajasthan, completed his Brahmasphutasiddhanta. It is the earliest surviving text to treat zero as a number in its own right, with rules for adding, subtracting and multiplying with it, as well as with negative numbers, which he called debts, and positive ones, fortunes. Earlier cultures had used zero as a placeholder in written numbers, but Brahmagupta's rules made calculations possible. The decimal place-value system, with zero, passed to the Islamic world and then, through Fibonacci, to Europe. He also gave a formula for the area of cyclic quadrilaterals.
Before and after
- April 625 CEBattle of Sarus
- 9 January 626 CEBirth of Husayn ibn Ali
- from June 626 CE to July 626 CESiege of Constantinople
- from 627 CE to 629 CEThird Perso-Turkic War
- 628 CEBrahmagupta sets out the rules for zero
- March 628 CETreaty of Hudaybiyyah
- 629 CEConquest of Mecca
- from 629 CE to 1050Arab–Byzantine wars
- from 629 CE to 645 CEXuanzang travels from China to India
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The era
This moment belongs to the Medieval world (500 CE to 1500 CE), kingdoms, faiths and trade routes. You can also browse everything in the 7th century.