Olivetti Divisumma 18: A Design Classic

I have lusted after the Olivetti Divisumma 18 since I first laid eyes on one in a book while I was in design school, some 20 years ago. Aside from in a museum I have never seen one in person…until now. After years of searching, I was able to score one on eBay that is in mint condition, and complete with all packaging, manual, even extra rolls of the foil tape used for printing the calculations (since it has no digital display).

This photo gallery will take you through the whole out of box experience, and show off the calculator from various angles.

The Divisumma 18 was designed in 1972 by the famous designer/architect Mario Bellini, who did a number of designs for Olivetti. It was pioneering in its form, use of color, and use of a rubber membrane that covers the keys to create a seamless, sleek look. This design of “volcano buttons” has since been mimicked on numerous products to the present day. Bellini used this style of button on a couple of other calculators and also typewriters. The keys have a pleasant mechanical click to them - they don’t feel at all like the mushy rubber keys we expect on calculators today. The extruded profile approach to form is also again back in style today.

The 18 is surprisingly large - you’ll see one photo in the slideshow with a pen sitting on top of it. It feels great in the hand, but it’s not a handheld calculator. More of a stylish desk calculator.

Here’s a page with more details (including photos of the internals), and a page about the calculator from the Museum of Modern Art, which has it in its permanent collection.