50 years have passed since the introduction of the first scientific pocket calculator HP-35

Have you ever realized that typing numbers on computer keyboards, calculators or cash registers is different from how they are entered on landlines and mobiles? Where did the split in what should be at the top left? An interesting question that cannot be answered with certainty. But there are two plausible theories.

The origin of calculators and numeric keypads

One explanation is mathematical. According to Benford’s law lower digits are more likely to appear in the numbers. In a study of tens of thousands of numbers, Frank Benford came to the conclusion that the most common in them was one, then two, three to nine.

For this reason, it makes sense to place the first digits down where they are more easily accessible and closer to Enter / Equals or the plus operator, which is also the most used. And because Western languages ​​use left-to-right notation, the bottom line looks like 123.

Benford described his conclusion in 1938 in the study The Law of Anomalous Numbers. The first electronic calculators came only in the 50’s, so they could use this knowledge. On the contrary, older mechanical calculators usually did not even use numbers in a grid layout, but in a row.

Origin of phone buttons

For phones, Benford’s law doesn’t make sense because the numbers aren’t random, but follow a certain system of prefixes. The current button layout is the responsibility of the engineers from Bell Labswho in the 1950s sought a replacement for the former rotary dial.

They started with number one at the top, and according to their research, dialing on a button dial with line 123 at the top suited them best. But zero as the tenth digit ended up like the calculators. For phones, however, this could be justified because the zero was at the bottom of those rotary dials.

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