Teaches pilots to solve aviation math problems mentally, without calculators. Covers essential areas like fuel planning, temperature conversions, and time-speed-distance calculations. Offers practical ...

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 ...

Long before calculators existed, civilisations across the globe developed ingenious mental calculation systems that could solve complex problems in seconds. These time-tested methods are experiencing ...