Septenary numeral system

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Septenary, Septimal, or Base 7 is a number system that uses the digits of 0-6. In nearly all fractions in the septimal system, there are repeating decimals.

Historical Uses

There is some evidence that certain Uralic groups used a base 7 counting system in roughly 500 BC. This is shown through the similarity of the number 7 in these languages and that the introduction of further numbers occurred much later. It is shown that the Selkup language use the decimal system, but that there was some presence of a septenary system.

Days of the Week

The days of the week use a base 7 counting system. It originated in Ancient Babylonia as a way of dividing a moon cycle into 4 weeks. Additionally, there were 7 easy to see astronomical bodies that were important in many societies. They were the sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. This was later adopted by Alexander the Great in Ancient Greece and then Constantine in the Roman Empire. Some attempts to change the 7 day week have been made with the French Republican Calendar.

In Works

Ivan Panin, a Russian mathematician, was reading the Old Testament in Hebrew. He found that there was a strange affinity for the number 7 and multiples of 7 in the book. This was found to be beyond chance because this affinity could appear over 70 times per passage. This suggests that there may have been a septenary counting system in place used by some during the creation of this book.

The Defiance TV Show is one concerning new species arriving to Earth. It was made by Rockne S. O'Bannon, Kevin Murphy, and Michael Taylor. It was released on Syfy TV. In this TV show, David J. Peterson was hired to design the Indojisnen language. He designed this language to associate with a septenary counting system.

In Western Music

In music theory, there are 12 total notes. There are 7 natural notes and 5 sharps/flats. Supposedly there is this uneven ratio because the human mind may only be able to hold 7 items in short-term memory. Western musicians count their notes in groups of 7.

In Astronomy

In many ancient societies, there were 7 classical planets. These were the Sun, the Moon, Mercury, Venus, Mars, Jupiter, and Saturn. In many of these societies, these planets had cultural significance. In most of these societies, they represented elements with Venus representing water and Mars representing fire and so on. In several cases, these planets were associated with organs or humors in the body with the Sun representing the heart and the moon representing kidneys or Jupiter with blood. Additionally, these planets gave way to the 7 day week.

In Other Science

The 7±2 “rule” is a psychological concept proposed by George Miller that states that the human short term memory can only hold roughly 7 objects at one time. This is the justification for many uses of counting objects in groups of 7. This is possibly why there were 7 classical planets in societies across Eurasia and possibly why western music has 7 major notes.

References

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