Agner Krarup Erlang developed the mathematical formulae that underpinned the design of telephone networks from the 1920s.
He passed his final school exam with distinction when he was just 14 and become a schoolteacher when he was only 15! A few years later, he studied mathematics and natural science at Copenhagen University, where he developed a fascination for problems of geometry.
His work on probability theory led him to join the Mathematical Association, where he met Johan Jensen, chief engineer at the Copenhagen Telephone Company. Jensen persuaded Erlang to join the telephone company and find a solution to the problem of waiting times for telephone calls. This led to the publication of his first paper 'The Theory of Probability and Telephone Conversations' in 1909.
His later work on the characteristics of telephone networks was soon adopted by telephone companies throughout the world, and his name lives on as the unit used to measure telephone traffic.
