Why are there 12 numbers?

If someone asks how many hours are in a day the answer is simple 24 hours.

But look at a traditional wall clock and you will notice something interesting. Its round face usually has 12 numbers with two hands showing the hours and minutes. We see this design so often that most people rarely stop to ask why clocks look this way.

Why are there 12 numbers? And why is 12 always placed at the top?

Clocks were inspired by Sundials

The story goes back thousands of years to sundials which were used to tell time by tracking the movement of the Sun across the sky.

When mechanical clocks were developed early clockmakers followed the same basic system used by sundials.  This also explains why the hands of traditional clocks move in a clockwise direction.

Why are there 12 numbers?

The use of 12 divisions has roots in ancient civilizations particularly the Babylonians who used a mathematical system based on 60. Later, ancient Greek mathematicians adopted similar ideas when dividing circles and measuring time.

The Greek astronomer Hipparchus used the 360 degree division of a circle. Later around the 2nd century Ptolemy divided each degree into 60 smaller parts.

These developments eventually influenced the way we measure time including minutes and seconds.

Why is 12 at the Top?

There is also a simple historical reason for placing 12 at the top. On a sundial around midday the Sun is at its highest point and the shadow is at its shortest.

This position became associated with 12 o’clock. When mechanical clocks replaced sundials, the traditional arrangement was largely kept.

Over time the familiar clock face with 12 at the top became the standard design we still see today.

So, the next time you look at a wall clock remember that its simple design is the result of centuries of mathematics astronomy and timekeeping traditions