Bhaskara I, also known as Bhaskara Acharya or Bhaskara the First, was a 7th-century Indian mathematician and astronomer. He was born in 600 CE in the town of Vijjadavida, near present-day Bijapur in Karnataka, India. Bhaskara I is often considered one of the earliest mathematicians and astronomers in Indian history. Celebrated for his significant contributions to mathematics, he is particularly known for pioneering the Hindu decimal system. As a devoted follower of Aryabhata, Bhaskara wrote a critique titled 'Aryabhatiyabhasya' in 629 CE, considered the oldest Sanskrit work in the fields of mathematics and astronomy.

The works of Bhaskara I are not as well-documented or preserved as those of later Indian mathematicians, and much of his contributions are inferred from references in later texts. One of the main works attributed to Bhaskara I is the "Mahabhaskariya," a commentary on the Brahmasphutasiddhanta, which was originally written by Brahmagupta. Comprising 8 chapters, 'Mahabhaskariya' delves into mathematical astronomy, exploring the correlation between cosine and sine and presenting an approximation formula for sin x. The book also addresses planetary longitudes, planetary conjunctions, solar and lunar eclipses, celestial bodies, lunar crescents, risings, and settings. Additionally, it elucidates the relationship between the sine of angles greater than 90°, 180°, or 270° and those less than 90°. Bhaskara I is credited with providing the Pell Equation (8x² + 1 = y²).

Bhaskara I's legacy is, to some extent, overshadowed by the works of later Indian mathematicians, such as Brahmagupta and Bhaskara II. Bhaskara I's influence is often acknowledged through references and commentaries made by later scholars who valued and built upon his contributions to the field of mathematics and astronomy.