apart from math, what else interested him?
Astronomy
Brahmagupta
Some of the important contributions made by Brahmagupta in astronomy are his methods for calculating the position of heavenly bodies over time (ephemerides), their rising and setting, conjunctions, and the calculation of solar and lunar eclipses.

what is the parity of zero? The quality of an integer being even or odd—is even. who invented the number zero? Indian mathematician Brahmagupta is this number an even or odd number? Even number what is the main reason for it being an even number? Zero is an integer multiple of 2, namely so zero is even. during which year was the mathematician born? 598 CE where was he born? Bhillamāla, Gurjaradesa
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Brahmagupta [SEP] Astronomy
2. In the same way that the half seen by the sun of a pot standing in sunlight is bright, and the unseen half dark, so is [the illumination] of the moon [if it is] beneath the sun. 3. The brightness is increased in the direction of the sun. At the end of a bright [i.e. waxing] half-month, the near half is bright and the far half dark. Hence, the elevation of the horns [of the crescent can be derived] from calculation. [...]