"Bhaskara... is said to have been... lineal successor of Brahmagupta as head of an astronomical observatory at Ujein... sometimes written Ujjayini. He wrote an astronomy... Lilavati is on arithmetic... Bija Ganita is on algebra; the third and fourth... on astronomy and the sphere... [I]t is... probable that Bhaskara was acquainted with... Arab works... written in the tenth and eleventh centuries, and with... Greek mathematics... transmitted through Arabian sources. ...[F]rom the ...table of contents ...Arithmetical progressions, and sums of squares and cubes. Geometrical progressions. Problems on triangles and quadrilaterals. Approximate value of π. Some trigonometrical formulae. ..[T]he book ends with a few questions on combinations. This is the earliest known work which contains a systematic exposition of the decimal system of numeration. ...Chapters on algebra, trigonometry, and geometrical applications exist, and fragments of them have been translated by Colebrooke. Amongst the trigonometrical formulae is one... equivalent to... d (\sin \theta) = \cos \theta d \theta."