Many of us take calculators for granted especially now when you can easily pull up a calculator app on any phone. But before its modern form, the device went through a long and arduous evolution. The arithmometer - an invention by Charles Xavier Thomas de Colmar in 1820, was the first commercially successful calculating machine to complete all four basic operations — addition, subtraction, multiplication and division. In the 20th century, the Thomas Arithmometer was the gold standard calculation