Brahmagupta was a prominent Indian mathematician and astronomer in the 7th century CE. From arithmetic to algebra and geometry to positions of heavenly bodies, Brahmagupta's contributions placed him as one of the greatest mathematicians of his time. He influenced international scholars and is still remembered as the mathematician who introduced clear arithmetic rules involving zero and negative numbers.
Origin Story of Brahmagupta: Brahmagupta's life began in 598 CE in Bhillamala, now known as Bhinmal, in Rajasthan. His father, Jishnugupta, was a scholar, and Brahmagupta grew up learning astronomy and mathematics. In 628 CE, at 30 years of age, Brahmagupta wrote his first great work, the Brahmasphutasiddhanta ("Correctly Established Doctrine of Brahma").
A few decades later, in 665 CE, he wrote a second treatise called Khandakhadyaka. Soon after these works, Brahmagupta moved to Ujjain, the leading centre of mathematical astronomy in India, and became head of the observatory there.
The Magical Number Zero: Brahmagupta's books are filled with many mathematical rules and formulas. He clearly explained the number zero and how it works, defining it as what you get by subtracting a number from itself, and gave rules such as "adding or subtracting zero does nothing to the number" and "any number multiplied by zero is zero".
Algebra: Brahmagupta made major advances in algebra, solving complex equations that other mathematicians had not solved. He liked to work on complex arithmetic problems, such as finding unknowns in interest and loan puzzles.
Numbers and Shapes: Brahmagupta used everyday terms in explaining maths, calling positive numbers "fortunes" and negative numbers "debts". He discovered remarkable formulas in geometry, including his famous formula for finding the area of a cyclic quadrilateral, and gave a way to compute values of sine functions.
Contributions in Astronomy: Brahmagupta calculated the length of the solar year as about 365 days and 6 hours, very close to the true value. His books explain the motions of the planets and the timings of lunar and solar eclipses. He also wrote that "heavy things fall down to the earth by a law of nature, for it is the nature of the earth to attract and to keep things" - an early understanding of gravitational attraction.
Legacy and Recognition: About a century after his death, Brahmagupta's work was translated into Arabic, helping spread the Hindu-Arabic numeral system (including zero) to Arab and later European mathematicians. Historian George Sarton called him "one of the greatest scientists of his race and the greatest of his time". Bhaskara II honoured him with the title "Ganita Chakra Chudamani", meaning "The Gem of the Circle of Mathematicians".
A modern metal sculpture of Brahmagupta stands in Shaheedi Park, Delhi, celebrating his contributions. Students still learn Brahmagupta's rules for zero and his famous formulas in school today.