Problems from Indian mathematics.
Project Brahmagupta is an archive of १०८ problems in mathematics and computation, drawn from and inspired by the works of Indian mathematicians.
Brahmagupta Quadrilaterals
Brahmagupta's formula for the area of a cyclic quadrilateral. Count the integral cyclic quadrilaterals with distinct sides a ≤ b ≤ c ≤ d and a + b + c + d ≤ 60.
View sample → Sample 0.2Vargaprakriti
The nth hexagonal number is hₙ = n(2n − 1). Find the second smallest hexagonal number that is also a perfect square.
View sample → Sample 0.3Cow Enumeration
A cow bears one calf a year; each calf breeds from its fourth year. Starting from a single calf, count the herd after 2¹⁰⁸ years, modulo 10⁹ + 7.
View sample →FAQs
A few common questions. Anything else? Send a note via the contribute page.
What is Project Brahmagupta?
An open archive of 108 problems in mathematics and computation, inspired by the works of Indian mathematicians from antiquity to the present. Some problems are classical and some are modern, written in the same spirit.
When did it launch?
July 1, 2026. From that day, one problem is unlocked each midnight India Standard Time, for 108 days.
Who is this for?
Anyone with a working knowledge of mathematics who enjoys turning ideas into code. The problems range in difficulty: some are accessible with high-school algebra, others reward graduate-level number theory or careful computation.
Can I submit a problem?
Yes. The contribute page accepts problem proposals. We are looking for problems honest to Indian mathematical material, either drawn from an Indian source, or new problems that share the spirit of the collection.
Is it open source?
Yes. The site code is MIT-licensed; the content (problem statements, prose) is licensed under CC BY 4.0. The repository lives on GitHub.
Will solutions be published?
Not on the site. In keeping with the Project Euler tradition, problems are released without solutions: you discover them by solving. A discussion forum may follow once the series is complete.