"Dirty Dozen" We have borrowed this term from www.organic.nz. They use this term for the food substances that has the maximum amount of pesticide residue. If you wish to know them please click on their web site. We are concerned with the mathematics of digit 12. ( By the way what is the other meaning of digit?) Did you ever wonder why they sell eggs by the dozen? Why a foot ruler is divided into 12 inches? Day time is normally 12 hours? A year has 12 months? Let us try to analyse the number. They are the first two digits 1 and 2. 1 + 2 = 3, ……3 + 1 = 4………… (3 and 4 add up to 7),…… 7 + 5 = 12.
Here are a few more: A Triangle with 3 equal sides has angles of 12 x 5 degrees. = 60 degrees. A circle has 12 x 30 degrees = 360 degrees. Well that’s not all. Remember the Pythagoras Theorem. If you have a triangle with sides equal to 3, 4. And 5 it will have an angle equal to 90 degrees. The value of a corner in a perfect square. The ancient farmers that grew food in the Nile valley used a rope divided into 12 parts using knots. With flood waters that inundated their farming land their borders disappeared. They used this rope to measure the land they cultivated. Later during the floods that lasted over three months, they built gigantic Pyramids. They used this rope to get the perfect corners. The rope with 12 divisions could easily bent and folded to a triangle with the sides 3, 4 and 5 the sum of which is 12. This is what Pythagoras learned from the Egyptians. It is also a number more convenient to use than 10. Compare the fractional values of 10 and 12: ½ of 10 = 5, 1/3 of 10= 3. 333333, ¼ = 2.5 ½ of 12 = 6. 1/3 of 12 = 4. ¼ of 12 = 3 ( Observe how neatly you get whole numbers.) The factors of 10 are only 2 and 5. The factors of 12 are 2,3, 4 and 6.This is the reason for getting whole numbers for the fractions of 12. The beginning the system of 12. We think the 10 system is good as we have 10 fingers. The ancient Babylonians counted sheep up to 60 using fingers. When the thumb is used for pointing the bones in the fingers, each finger has 3 bones. The four fingers have 12 bones. After 12 fold the thumb of the other finger. That would be 1 set of 12. As you have 5 fingers 12 times 5 gives 60.

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