It is the 1970s, established typewriter brands of course had to venture out into the exciting new world of the electronic calculator. This pleasing calculator was made in 1972 for the Litton Imperial Typewriter Company under it's Royal brand as the Royal Digital 5-M.
The calculator had five functions, the four basic arithmetic functions and percentages thanks to algebraic logic, and also had memory. The calculator had an 8 digit green vacuum fluorescent tube display.
