For decades, a math puzzle has stumped the smartest mathematicians in the world. x 3 +y 3 +z 3 =k, with k being all the numbers from one to 100, is a Diophantine equation that's sometimes known as ...

Some even believe that regular mental exercises can help delay the symptoms of dementia. Puzzles come in various forms, and this particular brainteaser is so challenging that it appears only those ...