The world Maths day, is supposed to be held every 1st Wednesday of March. It is the largest online maths competition, and involves playing 60 sec. Games with the platform heavily based on Live Mathletics. The contest has age appropriate mental math problems that test the accuracy and speed of the students as they compete with students across the globe. It is a bi-annual even, since 2007, open to students between 4-18, patronized by the UNICEF organized by 3P learning.
This year however the event is scheduled for 14th October.
Parwatisingari's Weblog 
Never knew a day for Maths exist. Nice