The bat-and-ball problem is a famous math puzzle that more than half of people—even Harvard graduates—get wrong. It's ...

Get your timer out and see whether you can remember the golden rule from grade school math class.

The question goes: "A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost?" Is your knee-jerk response that the ball costs ten cents? That is a ...

Add Yahoo as a preferred source to see more of our stories on Google. We like to think that we're pretty good at math, especially after years of schooling. But every once in a while, a simple ...