How was the calculator invented? How did it go from something the size of a table to something that could be carried in your pocket, the must-have gadget of the 1970’s and 80’s?

Tim Harford unpicks the history of the calculator with Keith Houston, author of Empire of the Sum: The Rise and Reign of the Pocket Calculator.

Presenter: Tim Harford Producer: Debbie Richford Production Co-ordinator: Brenda Brown Series Producer: Tom Colls Sound Mix: Hal Haines Editor: Richard Vadon