Articolo meraviglioso, che cerca di capire una cosa che in tanti ci siamo chiesti, da sempre: perché il tastierino numerico dei telefoni e quello delle calcolatrici (e dei computer) sono orientati diversamente.

Picture the keypad of a telephone and calculator side by side. Can you see the subtle difference between the two without resorting to your smartphone? Don’t worry if you can’t recall the design. Most of us are so used to accepting the common interfaces that we tend to overlook the calculator’s inverted key sequence. A calculator has the 7–8–9 buttons at the top whereas a phone uses the 1–2–3 format.
Subtle, but puzzling since they serve the same functional goal — input numbers. There’s no logical reason for the inversion if a user operates the interface in the same way. Common sense suggests the reason should be technological constraints. Maybe it’s due to a patent battle between the inventors. Some people may theorize it’s ergonomics.
With no clear explanation, I knew history and the evolution of these devices would provide the answer. Which device was invented first? Which keypad influenced the other? Most importantly, who invented the keypad in the first place? [link]