This question is actually more complicated than you would think. We are continually trying to find more and more decimals of Pi. We will never know the full value of Pi because the numbers never stop and never repeat, they go on into infinity.
We do know the first recorded value of Pi was recorded by and Egyptian scribe around 1650 B.C.E. He said "Cut off 1/9 of a diameter and construct a square upon the remainder; this has the same area as the circle." This means that the ratio of circumference to diameter is 256/81 or 3.16049...
None. The existence of Pi was estimated by the ancient Egyptians, ancient Indians, and Babylonians many hundreds of years, B.C. The Greek philosopher, Archimedes, was later able to calculate the value of Pi using geometry to a great degree. It wasn't until 400 - 500 A.D. that Chinese mathemetician Zu Chongzhi found that 553/113 was a very accurate approximation of the value of Pi, so much so that his value held for the next 900 years.
douchbag
Archimedes of Syracuse is said to be the first mathematician to make a systematic attempt to estimate pi in the third century BC.
Pythagoras
No one has ever discovered the real value of pi because it is an irrational number which means it can not be expressed as a fraction and only an approximation was given to it.
The Egyptians in 2000 b.c.
Egyptians and Mesopotamians and babylonians
The first to find the value in pi were the Babylonians and Egyptians.
The first written evidence that has been found of people finding the value of pi is in an Egyptian papyrus and Babylonian tablets about 1900 BC, however, some historians believe that the ratio of the perimeter to height of pyramids built in Egypt as early as 2613 - 2589 BC suggests that Egyptians already had made approximations of the value of pi at that time.
No one because the true value of pi can never be found because it is an irrational number that can't be expressed as a fraction.
3.14159..... Thomas Jefferson he is a very smart person
The ancient Babylonians from around 1700 BC used pi = 3.125. The name of the person who calculated that value was not recorded.
aryabhatta discovered it as 3.1416