Slide adder pocket calculators (14 h 39 m, 21 nov 2018 año – 14 h 49 m, 1 jul 2019 año)

Descripción:

They remained the only portable calculation aids until the Orthographe. they were soon known as a "Troncet", millions of them were sold and they were on the market until the 1970s. Contrary to slide rules, these "slide adders" were digital devices, but their mechanism is more related to slide rules and the abacus than to mechanical calculators.

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