A brief history of the numeric keypad

Here is where the story gets interesting. Why did Felt choose to display the numbers in a 9 to 1 sequence? It wasn’t a widespread notion at the time. After all, the knowledge of arithmetical devices was not as widespread. A reasonable answer could be tied to some mechanical decisions, possibly related to the method of complements and the fact that keys were pressing levers connected to rotating drums (Durant, 2011). The longer stick was equal to a longer rotation, which meant to be the number 9, as opposed to number 1 which required a shorter rotation — a suggestion from an older concept by Parmelee. Another interesting explanation — from a modern design standpoint — goes beyond the mechanical reasons. According to the Comptometer Manual, operators were meant to input numbers by using the lowest values on the keyboard. For instance, in order to enter “9 cents”, the operator was not supposed to press the 9 key at the very right column. Instead, they were to press, in sequence, the 4 a ... Read full article.