
HP introduced the world’s first calculator watch (HP-01) in 1977, at the price of $650 ($2109 in 2005 dollars).
It computes. Whether interactively or not, it adds, subtracts, multiplies, divides; performs chain, mixed chain, serial, and mixed serial calculations; finds percentages, changes signs. Computes to 11-digit accuracy and rounds the display to seven digits.
[via ModernMechanix]