In algebra, Brahmagupta's identity says that,

In geometry, Brahmagupta's theorem states that if a cyclic quadrilateral is orthodiagonal, 

The book was written completely in verse and does not contain any kind of mathematical notation. Nevertheless, it contained the first clear description of the quadratic formula (the solution of the quadratic equation).

The book was written completely in verse and does not contain any kind of mathematical notation. Nevertheless, it contained the first clear description of the quadratic formula (the solution of the quadratic equation).

 Brahmagupta first described gravity as an attractive force

• His mathematical foundations in fields like Algebra, Arithmetic, Squares, and Cubes Zero Diophantine Analysis ,Pythagorean triplets ,Pell's equation, Geometry Brahmagupta's formula ,Triangles Brahmagupta's theorem ,Pi ,Measurements and constructions, Trigonometry, Sine table and Interpolation formula

• Astronomy - He explains that since the Moon is closer to the Earth than the Sun, the degree of the illuminated part of the Moon depends on the relative positions of the Sun and the Moon, and this can be computed from the size of the angle between the two bodies.

• Further work exploring the longitudes of the planets, diurnal rotation, lunar and solar eclipses, risings and settings, the moon's crescent and conjunctions of the planets, are discussed in his treatise Khandakhadyaka.