Olivetti started producing 10-key mechanical add-listers in the mid-1940s, and successfully specialised in these machines until superceded by electronics models. In the U.S.A. they were sold under the Underwood name - see the
article "Olivetti Underwood Electro-Mechanical Calculators" in the Collecting Calculators section of this site.
Olivetti is famous for employing some of the leading designers to produce very stylish products, including the calculators, some of which are considered design classics. See the article "Olivetti Electronic Calculators and the Designs of Mario Bellini" in the Collecting Calculators section of this site.
The company introduced one of the first programmable electronic calculators in the mid-1960s, the Olivetti Programma 101, and continues to sell calculators today.
Examples of Olivetti calculators