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

Discover a mind-blowing trick with measuring tape that will change the way you see this common tool. Featured Products: - ...

Take tape measures, once a palm-sized object that housed a metal ribbon that could snap back enthusiastically -- has been transformed into a palm-sized device with with a laser inside. Yup, the ...