Starting with hands, abacus and slide rule, humans have always reached for tools to simplify math. Pocket-sized calculators ushered in modern mathematics, helped build the atomic bomb, took us to the bottom of the ocean and accompanied us to the moon. The pocket calculator changed our world, until it was supplanted by more modern devices that, in a cruel twist of irony, it helped to create. The calculator is dead; long live the calculator. In this witty mathematic and social history, Keith Houston transports readers from the nascent economies of the ancient world to the Second World War, where a Jewish engineer calculated for his life at Buchenwald, and into the technological arms race that led to the first affordable electronic pocket calculators. At every turn, Houston is a scholarly, affable guide to this global history of invention. Empire of the Sum will appeal to math lovers, history buffs and anyone seeking to understand our trajectory to the computer age.

"The book provides a breezy mathematical history tour through the development of number systems, slide rules, mechanical calculators and microchips." -- Jeffrey M Perkel - Nature
"Houston's sprightly history aims to give the calculator the recognition it deserves as a stepping stone to the digital era... He makes a convincing case, in sum, for the significance of the calculator." -- The Economist
"[An] enlightening history" -- Pablo Scheffer - The Times Literary Supplement
"Fascinating […] a cre­ation story of tech breakthroughs begetting first-of-their-kind digital calculators." -- Belinda Lanks - The Wall Street Journal
"Houston’s narrative is full of oddballs, many of them brilliant…" -- Alexander Nazaryan - The New York Times Book Review

Keith Houston is the author of Face with Tears of Joy, Empire of the Sum, Shady Characters, and The Book. His writing has appeared in The New York Times, The Wall Street Journal, the Financial Times, and on Mental Floss, BBC Culture, and Literary Hub. He lives in Linlithgow, Scotland.