A man has been left unable to solve his seven-year-old son's maths homework, admitting he doesn't know where to start – and even the class teacher was confused ...

A previous puzzle also left many scratching their heads ... and encourage people to test their problem-solving skills. Many ...

Some users quickly spotted the pattern, while others were left scratching their heads. Mathematical brain teasers have a unique appeal. Unlike traditional school problems, they are presented as ...