[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.
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.
An early version of Cheryl's Birthday, with different names and dates, appeared in an online forum in 2006.
[4] The SASMO version of the question was posted on Facebook by Singapore television presenter Kenneth Kong on April 10, 2015, and quickly went viral.
[3] Kong posted the puzzle following a debate with his wife, and he incorrectly thought it to be part of a mathematics question for a primary school examination, aimed at 10- to 11-year-old students,[5] although it was actually part of the 2015 Singapore and Asian Schools Math Olympiad meant for 14-year-old students, a fact later acknowledged by Kong.
[6] The competition was held on 8 April 2015, with 28,000 participants from Singapore, Thailand, Vietnam, China and the UK.
SASMO's executive director told the BBC that "there was a place for some kind of logical and analytical thinking in the workplace and in our daily lives".
[11] This was rejected by the Singapore and Asian School Math Olympiads as an invalid answer.
Albert therefore is able to deduce that "Bernard doesn't know" because he heard a month that does not contain those dates (July or August).
Realizing this, Bernard can rule out May and June, which allows him to arrive at a unique birthday even if he is given the dates 15 or 16, not just 17.
On May 14, 2015, Nanyang Technological University uploaded a second part to the question on Facebook, entitled "Cheryl's Age".
[14] 144 can be decomposed into prime number factors by the fundamental theorem of arithmetic (144 = 24 × 32), and all possible ages for Cheryl and her two brothers examined (for example, 16, 9, 1, or 8, 6, 3, and so on).
[15] This sequel was also written by Dr Yeo, the original author of "Cheryl's Birthday".
The puzzle states: Albert, Bernard and Cheryl became friends with Denise, and they wanted to know when her birthday is.