A mind-boggling mathematics problem purportedly set as homework for a Primary 5 pupil turned out to be a question meant for upper secondary students taking part in high-level maths contests.
A photograph of the question, aimed to test logical thinking, was posted by TV talk show presenter Kenneth Kong on Facebook on Saturday and was later shared almost 4,000 times.
Mr Kong told The Straits Times it was sent to him by a friend whose Primary 5 niece had asked for help with an assignment last week.
It stumped netizens of all ages and sparked discussion on the use of such questions for pupils at any level.
More than 4,200 readers also shared the story through The Straits Times' Facebook page, with many exchanging solutions to the problem and expressing disbelief that Primary 5 pupils were expected to solve it.
Henry Ong, founder of the Singapore and Asian Schools Math Olympiad, clarified that the question was from its contest for Secondary 3 and 4 students held last Wednesday.
Students from more than 30 secondary schools here took part in the competition.
"This is a difficult question meant to sift out the better students," he said in a reply to Mr Kong.
Mr Ong told The Straits Times yesterday that in his 10 years of organising such competitions for Primary 2 to Secondary 4 students, questions have never been leaked.
"We were very surprised because students were not allowed to keep their handphones on them," he said.
The student who took the photo of the question is liable for disqualification from the competition, but he acknowledged that the culprit would be hard to find.
The Ministry of Education told The Straits Times that the question was not part of the Singapore primary or secondary maths syllabus, and was not reflective of the type of questions that are set in its maths assessment.
Parents and tutors added that it did not test primary school maths concepts.
Michael Tan, 46, a church worker who has a son in Primary 5, said: "It's fine if schools use them for fun and to challenge students, but these sort of questions should not be in exams."
Tan Weiqiang, director of Junior Wonders Tuition Centre, said some schools may want to "stretch their brightest students" with such questions, but it is "very uncommon".
"This isn't what mainstream school students should be worrying about," said the former primary school maths teacher.
Wallace Wong, a maths tutor and co-founder of tuition centre Study Room, said: "This isn't an examinable question but it could have been used to get kids thinking and interested in the subject."
Additional reporting by Jalelah Abu Baker
Try out the puzzle at bit.ly/1JDwjua
This article by The Straits Times was published in MyPaper, a free, bilingual newspaper published by Singapore Press Holdings.