Review: Addifix 9 Mechanical Number Cruncher and Pocket Calculator

While trying to explain the meaning of the carry digit during addition an subtraction to my oldest son, I’ve given him a nice little device to play with: the Addifix-9 number cruncher.

I’ve briefly mentioned this device before in a post. This time I’ve made a short video about the mechanical calculator in action and present more details:

In the 1950s/60s The Addifix series was sold as “Addifix-9 Taschenrechenmaschine” by the German mail-order company Neckermann. Its predecessor was the Addiator from Carl Kübler which was sold since the early 1920s  [Source:]. The underlying mechanical principle is quite old (an documented example is the mechanical calculator by Claude Perrault from the 17th century).

The Addifix is a pocket-sized (13 x 9 cm) slide adder that can be used from both sides – one side for addition and one for subtraction. The slides (one for each digit) are handled with a metal stylus.

Addifix-9 hand calculator (number cruncher)

I recently rediscovered an old hand computer, which was in my desk drawer for ages: an Addifix-9.
Addifix-9 Hand CalculatorThe Addifix was sold in the 1960s by a no longer existing German mail-order company called Neckermann. (Well: actually the brand Neckermann still exists, but under a new owner.) A stylus is used to make additions on the one side, and subtractions to the other.

By the way: I really like the English name for this kind of tool: number cruncher… 🙂 (And no, it’s neither a slide rule nor an abacus, although similar.)

A video demonstrating the calculator is included in a newer post.