Rotary Telephone

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Frequently Asked Questions...

Why do numbers on a telephone and those on a calculator start from opposite directions?

Best Answer...


While it is not known, officially, some good theories about the contrasting layout of keys on telephones and calculators exist. I'll list a few; my favorite theory is listed last.

First, regarding calculators: the earliest keypads existed for cash registers, with the numbers starting from Zero and working their way up - this likely seemed easiest for engineers. Calculators copied the cashier keypad, and it has stayed that way ever since.

For the phones, one theory points to a study done by Bell Labs in 1960. Trying to determine which layout was easiest for users resulted in the three-by-three grid with1, 2 and 3 across the top.

Another telephone theory is based on the layout of a rotary telephone. On a rotary dial, 1 is at the top right and zero is on the bottom. When designing the new touch-tone keypad, putting the 1 on the top-right didn't make much sense, because Western writing is read from left to right. But putting 1 on the top-left, and the subsequent numbers to the right, did make sense. Using that formula, the resulting rows fell into place, with zero getting its own row at the bottom. (Quoted entirely from source #1, below.)

However, my *personal* favorite theory is that the telephone's layout had to be changed to 1-2-3 at the top because this would best correspond to the alphabet letters associated with each key. ABC should certainly be on the top row, and to do this, the numbers' arrangement had to alter from that of a calculator.

Interesting, no?