Regarded as Brahmagupta's most influential book, the Brāhmasphuṭasiddhānta(-brah-ma-fut-ah-sidd-anta),
was an important book in the mathematical world. Containing 24 chapters on mathematics and astronomy, it is a significant book containing the first ever definition of zero and its operations. In the book we see how Brahmagupta imagined zero as a numeral and not just a symbol.
"As important as the Brāhmasphuṭasiddhānta is, not that many people even know it exists!"
~ E F Robertson
(Mathematics Professor at the University of St Andrews)
The book found its way to Baghdad. The most controversial idea to the Arabic mathematicians was the idea of zero as a numeral. It was dismissed but also accepted by some. The famous Persian mathematician Al-Khwarizmi used the ideas of zero from the Brāhmasphuṭasiddhānta to create algebra. The book ended up having a big impact on the world.
"Brahmagupta was the creator of zero, but the Brahmasphutasiddhanta was the messenger which spread zero all throughout the world."
~ Dakota Duffy
(Writer at the Scholarly Resources for the Study of Hinduism)
This is a Soviet commemorative stamp depicting the mathematician Al-Khwarizmi.
(Source-MuslimHeritage)