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For at least 3,000 years.
'pi' is the small case Classical Greek letter 'p', and means 'proportion'.
The Sumerian civilisation is thought to have calculated it.
They noticed that when a donkey is tethered to a pole to drive up water, it went round in a circle. The distance around the circle(circumference) was greater , the longer the tether was made (radius).
From this they deduced that the circumference was directly proportional to the diameter * 2 radii).
In algebraic terms
C is directly proportional to d
Equating
C = d * k ( k is a constant)
Hence dividing by 'd'
k = C/d
K was found to be always 3.141592.... and was given the name 'pi' , for proportion.
Hence today we use C = pid or C = 2pi*r
If you are learning about this in school , you will probably be given pi = 3.14, but this is only an approximation. A closer approximation is pi = 3.1416
However, 'pi' is an IRRATIONAL number, which casually means, the decimals go to infinity and are not in any regular order. Supa Dupa computers have calculated 'pi' to billions of places and still going.
A Classical Greek mathematician , Eratosthenes, in approximately 220 BC and using 'pi' calculated the Earth's circumference to a very high degree of accuracy. It took Christopher Columbus 1600 more years to actually prove the point.
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Why is pi an inrational number?
An irrational number has no end and pi is infinite and has no end, therefore pi is irrational. Note: There are computers that have been computing the number pi for a long time and there has been no end yet. The numbers just keep going on and on and there is no rhyme reason or pattern to it.
How many digits of pi have been discovered?
1.2411 trillion digits (1,241,100,000,000) digits of pi have been dicovered.
Why does pi exist?
cause pi is allways around us and without it we would probley die
How long has pi been known?
Since the Sumerian Civilisation. ~ 2000 BC. The ratkio of circumference to diameter, which is 'pi' has been known for over 4000 years. When the ancients investigated the ratio of curculaference to diameter of any sized circle, they always cam up wityh the same constant of proportion (pi). Ciircumferecne is directly proportional to diameter This is equated to C = k*d 'k' is the constant of proportion. Hence C/d = k ( pi = 3.141592.....) 'pi' is the lower case classical Greek letter 'p'. and is used from Classical Times for circular proportion.
Why is pi 3.14?
pi became 3.14 from a long division problem that is probably the longest number in the world.
