The Constitution of India designates the official language of the India as Hindi written in the Devanagari script. In India, 255 million people speak at least two languages and 87.5 million speak three or more languages.
Hindi
Hindi is the primary official language of India and had 422 million native speakers as of the 2001 Census. About 98.2 million Indians speak Hindi as a second language and 31.2 million speak it as their third language.
References
Multilingualism in India Wikipedia(Text) CC BY-SA