India contributed greatly to many areas including mathematics, science, philosophy, and medicine. Key contributions include developing the number system including zero, inventing algebra and trigonometry, calculating the time taken for earth to orbit the sun, establishing some of the earliest universities and institutions of advanced education like Takshashila and Nalanda, and establishing some of the earliest systems of medicine including Ayurveda. India was also a leader in many areas of science and technology throughout ancient times.