A Sinclair Executive pocket calculator, 1972.

This was the first electronic pocket calculator that could really fit into a pocket. Clive Sinclair (b 1940) was able to achieve this by reducing the power input demanded by the calculator chip. The calculator was capable of addition, subtraction, division and multiplication, and was able to store a constant. It was one third the size of any of its competitors in 1972 and cost half as much.