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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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How long has pi been known?
Since around 2000 BC. Even though it was only right to the first decimal.
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
What is the length around a 9 foot circle?
Circumference of a circle = 2*pi*radius or pi*diameter
What is the history of pi?
pi has been around for as long as we have had written records.Its approximate estimated value of Pi up to 5 decimal places is 3.14159 .Archimedes was the first person to estimate the correct value of pi
How long were mathematicians been studying pi?
Pi have been studied for over 10 centuries!!!
How long has pi been known?
Since around 2000 BC. Even though it was only right to the first decimal.
Did Albert Einstein invent pi?
No. Pi has been around for much longer. There's even a reference to it in the Bible.
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 long has deforestaion been around?
how long has deforestation been around
How long has guns been around?
As long as guns have been around.
What is the whole pi?
Pi has been calculated to over two trillion decimal places. I won't live long enough to type all of them.
How long is pi?
Pi has been calculated to over 1 trillion places, but it has an infinite number of places since it's sequence never repeats.
How long has the London eye been around for?
how long has the london eye been around for
How long has Mackenzie Falls been around?
As long as So Random has been around.
When was pi invented?
As a letter, pi has been around for around 3000 years; it has represented the following concept for just under 300. As a mathematical concept (the ratio of a circle's circumference to its diameter always being the same), pi has been used for around 4000 years.The concept of PI was written about 3,912 years ago, because the earliest known textually evidenced approximations of PI date from around 1900 BC. They are found in the Egyptian Rhind Papyrus. But only 306 years ago in 1706 AD William Jones was the first to use the Greek letter PI referring to the ratio of the perimeter to the diameter, which is constant for all circles.
