Why is National Mathematics Day celebrated on December 22? 
National Mathematics Day is celebrated on December 22, since 2012, after former Prime Minister Manmohan Singh made the declaration, to pay tribute to S Ramanujan and celebrate his birth anniversary. Ramanujan is known for his contributions to the theory of numbers and compiling over 3,000 mathematical results and equations. Notably, his 129th birth anniversary was observed on the day.