Today, the most used numeral system in the world is decimal (base 10) as it would be easier for humans to count by using their fingers. The civilization that first divided time into parts didn’t use decimal – and that’s why time is divided using base 12 and base 60 instead. In this article, we would explore how the ancient world calculates their time and how the system eventually grew into what it is in modern times.

What is the significance of base 12?

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An 1892 Sun Dial in Melbourne, Australia

The Egyptians are the first people to divide time into parts, with the use of Sundials. As early as 1500 B.C, they have created an advanced version of the device, dividing the time of the day into 12 parts. The number 12 has great meaning in their culture – it is the number of lunar cycles per year, and the number of finger joints on each hand (excluding the thumb). With Egypt being the center of the ancient world and cradle of all civilizations, other cultures have taken this device and adapted it for their own uses, created the clock we know today.

Why is a day 24 hours long?

Without artificial light, the ancient humans divided the day and the night into two different periods rather as part of the same day. This would create a question: why is nighttime also divided into 12 if there is no sunlight in the period?

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Everything was decorated pretty intricately back then

The Egyptians probably just try their best to find the number 12 in every place they could. Originally, they calculate the periods of the night based on the 36 stars that can be observed, however, due to the fact that some of those stars are just not bright enough and are obstructed during various parts of the night, the total number was reduced to 12. The 24 hours/day was born when they combined the two systems together.

Why is an hour 60 minutes long?

While the 24 parts/day concept was created pretty early, those parts are actually not as big as one another – the concept of fixed length hours was created much later. During the Hellenistic period in Greece, Greek astronomers finally created the system – properly dividing every day into 24 separately equal pieces.

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An ancient water clock from Egypt

The technique these Greeks used was actually developed by the Babylonians, whose base 60 is the main system. The reason for the number 60 is that it is the smallest number divisible by 1-6 and 10, 12, 15, 20, 30. This is why an hour has 60 minutes. The same thing was also applied to minutes to create 60 seconds - the base 60 system is also used to measure angles and geological coordinates.

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