Two mathematicians have proved that a straightforward question—how hard is it to untie a knot?—has a complicated answer.

Mathematician Grigori Perelman solved the Poincaré conjecture, and then rejected the $1 million prize that came with it.

A 529 college savings plan can be a powerful savings tool for future education expenses, as investments in the plan increase tax-free. While state tax benefits should be the first consideration for ...