Get out your timer and number two pencil to see if your arithmetic skills are still sharp.

Every few months, the Internet eats itself over some kind of viral riddle or illusion, each more infuriating than the last. And so, like clockwork, this maddening math problem has gone viral, ...

See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. A seemingly simple math problem that produced markedly different ...

A simple math problem sparked heated debate on Chinese education forums two years ago.