This logic was shared by a MediaCorp Channel 8 presenter Kenneth (江坚文) on Facebook on Saturday 11 Apr.

In his Facebook post he said “This question causes a debate with my wife …. and its a P5 question. #trickquestion

It is not known whether this is really a Primary 5 question or if it came from Singapore, but more importantly, can you solve the question?

*Editor’s note: This question is not meant for Primary 5 students, it is meant for Secondary 3 and 4 students. Please see the bottom of the article for the real origin of this question.*

This question causes a debate with my wife …. and its a P5 question. #trickquestion

Posted by Kennethjianwen on Friday, 10 April 2015


It seems that the Internet is split on which answer is correct:

Answer 1Answer 3

Answer 2


We are not sure which is the correct answer, but we sure liked these:

answer 8 answer 7 answer 6 answer 5 answer 4

Do you know the answer? Share it in the comments below!

*Update as at 13 April 10:12am* The correct answer has been provided by several of our readers, here’s one reader who explains it rather clearly:

p5 question answer

*Update as at 13 April 6.02pm* The Executive Director of the Singapore and Asian Schools Math Olympiad (SASMO) Mr Henry Ong sent in a clarification to

He said:

” The supposedly P5 question that went viral on the Internet on Apr 12, 2015 is actually a question from the Sec 3 and from the Sec 4 SASMO (Singapore and Asian Schools Math Olympiad) contests held on Apr 8, 2015 (see photo below). Being Q24 out of 25 questions, this is a difficult question meant to sift out the better students. SASMO contests target the top 40% of the student population and the standards of most questions are just high enough to stretch the students. Questions that test on logical reasoning are common questions in Math Olympiads. This year, about 28 000 students from Singapore, Brunei, Malaysia, Indonesia, Myanmar, Vietnam, Cambodia, Philippines, Thailand, China (including Hong Kong and Macau), Bulgaria, Uzbekistan, Mongolia and UK took part in the contests. We are pleased that this question has generated so much interest and ‘solutions’ on the Internet. For more information, please visit or*