Every so often it's good to exercise your brain with a math problem or two that forces you to recall principles you learned decades prior. As elementary as it might feel, you'd be surprised how easy ...

A red circle is inscribed inside a blue square. The arrangement leaves gaps in the square’s four corners, two of which are filled with smaller circles that just barely touch the big red circle and the ...

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 ...