Why do clocks have numbering from 1 to 12?

The most common numbering system in the world today is the decimal system (based on 10). This system probably originated from the fact that it was easier for people to count to ten using their fingers. But clocks use the duodecimal system.

Let’s start things from the beginning:

The earliest sundials were simple stakes placed in the ground, indicating the time by the length and direction of their shadow.

By 1500 BC, the Egyptians had developed a more advanced sundial. A T‑shaped rod was placed on the ground and, through certain adjustments, it divided the time from sunrise to sunset into 12 parts.

This division reflected the Egyptians’ use of the duodecimal (base‑12) numeral system. The significance of the number 12 lies in the fact that it corresponds to the number of lunar cycles in a year, or to the number of finger joints on each hand (three on each of the four fingers, not counting the thumb), making it possible to count up to 12 using the thumb.

Counting up to 12 with the thumb (duodecimal numeral system):

https://www.youtube.com/shorts/n8XvRpC1L3Q