Wow, this is one strange looking calculator! Some might call it stylish. In fact, in 1972 when it was introduced by Olivetti, it WAS stylish. It’s the Olivetti Divisumma 18 and is the wild creation of Mario Bellini one of the creative designers at the company at the time. It’s fairly large so I’m not sure it can really be classified as a hand held calculator though at that time in the early 70’s it was probably considered small. It’s 9 3/4″ x 4 3/4″ x 2″ and with it’s battery charger attached it’s just over 12″ long. So, yes it could be hand held but probably was more efficiently used as a desktop calculator. Bellini is also known for designing the Programma 101 desktop computer, Logos 50 and 60 calculators as well as the Divisumma 28 calculator.
The Divisumma 18 is made out of ABS plastic and has a rubber membrane that fits over the keyboard portion of the calculator and makes it look a little like something you’d use underwater. It’s only a four function calculator so would obviously only be used for basic calculations. Probably more of a eye catcher than a practical tool. Still, it changed the way many people looked at calculators which, up to then, were boxy, mechanical and fairly ugly. Bellini added some style to the genre that would affect electronics for some time to come.
As a calculating machine the Divisumma 18 isn’t anything special but it is such a noteworthy piece of design that it is included in the Museum of Modern Art in New York. The Divisumma 18 came with a detachable battery charger and built in printer. There is no display other than the printer. You can see the on/off switch just below the printer window. The small selector to the right of the on/off switch let’s the user choose between 0,2,3 or 4 fixed decimal places. The red light to the left serves both as a low battery charge warning and an error light.
The Olivetti Divisumma 18 was a very popular calculator so they are not really considered rare today. Nonetheless, demand for them is high from both calculator collectors, design aficionados and mid-century collectors. The most recent sale in August 2012 saw a Divisumma 18 with original box and all accessories sell for $500.00.