"Cheryl's Birthday" is a logic puzzle, specifically a knowledge puzzle.[1][2] The objective is to determine the birthday of a girl named Cheryl using a handful of clues given to her friends Albert and Bernard. Written by Dr Joseph Yeo Boon Wooi of Singapore's National Institute of Education, the question was posed as part of the Singapore and Asian Schools Math Olympiad (SASMO) in 2015, and was first posted online by Singapore television presenter Kenneth Kong. It went viral in a matter of days and also hit national television in all major cities globally.[3] Henry Ong, the Founder of SASMO was interviewed by Singapore's Mediacorp program FIVE hosts Chua En Lai and Yasmine Yonkers.