From Bounce:
In 1896 Alfred Binet, a French psychologist, carried out a simple experiment to find out. He compared the performance of two calculating prodigies with cashiers from the Bon Marché department store in Paris. The cashiers had an average of fourteen years experience in the store but had showed no early gift for mathematics. Binet gave the prodigies and the cashiers identical three- and four-digit multiplication problems and compared the time taken to solve them. What happened? You guessed it: the best cashier was faster than either prodigy for both problems. In other words, fourteen years of calculating experience had been sufficient, on its own, to bring perfectly ‘normal’ people up to and beyond the remarkable speed of prodigies. Binet concluded that calculating ability is more about practice than talent – which means that you and I could perform lightning-quick multi-digit calculations if we had the proper training.