No author has gone as far as Doerfler in covering methods of mental calculation beyond simple arithmetic. Even if you have no interest in competing with compute

Discover the Mental Math Secrets to Become a Human Calculator! Schools taught you a way to do math that works when you have a pen & paper. But the same methods,

Do high-speed, complicated arithmetic in your head using the Trachtenberg Speed System. Ever find yourself struggling to check a bill or a payslip? With The Tra

Written by two of the world's foremost authorities on mental calculation, The Mental Calculator's Handbook is essential reading for aspiring calculating prodigi