I have a friend who’s a world-renowned mathematician. He doesn’t think like me. Or you. Or, indeed, anyone else I know. This is a good thing — certainly for him. Especially as mathematicians of one ...

When Redditor u/Awecalibur reviewed his niece’s math homework, he wasn’t expecting to spark a family debate, let alone an internet one. But the fifth-grade math problem in question was anything but ...