For most of human history, doing arithmetic, while sometimes aided by devices like the abacus or adders, was fundamentally an act of human intelligence. In the 17th and 18th century, a few natural ...

FORT LEE — For 10 seconds, a series of 50 random three-digit numbers flashed on the screen. After another second, abacus master Jeonghee Lee announced she'd finished the mental addition, correctly ...

Ever dreamt of solving math problems in your head with the speed of a calculator? Mental math might seem challenging, but it's a skill attainable through the right tools and techniques. The abacus, an ...