“And have you noticed that not one of us has hair that matches his or her name?” “By golly, you’re right!” exclaimed Professor White. If the woman’s hair isn’t brown, what color is it?

Find one million consecutive positive numbers, none of which are prime.

Discover the hands-on game that builds your toddler's early math, motor, and thinking skills beyond crosswords or mazes.

Those of us who grew up coloring remember the cardinal rule: stay inside the lines. But those who pick up the Patterns of the Universe coloring book have to stay in the sines (and cosines and ...