Date 
By 
Value 
Circa 2000BC 
Ahmes 
The earliest recorded value of what became know as Pi was when Ahmes, a Greek mathematician, gave it a value of ^{32}/_{9} i.e. 3.55



Circa 200BC 
Archimedes 
It was Archimedes who calculated the first reasonably accurate value for Pi, when he first calculated it at 3+^{10}/_{71} = 3.14085 and finally 3+^{10}/_{70} = 3.14286





Ptolomy 
Ptolomy continued Archimedes work by developing a new value using the 60's denominator. His value was based on 3+^{8}/_{60}+^{30}/_{60}^{2 }that gave a value approaching 3.14166 to five decimal places. 

Circa 1650AD 
Adrian
Romain 
Assigned the Greek character Pi to the factor 

1699 
Adriaensz Métius 
Calculated the value of Pi as ^{355}/_{113} giving the current value of Pi to 10 decimal places i.e 3.1415926535 

1700/1800 
Various 
Calculating ever increasingly accurate values for Pi was a major exercise for mathematicians in the 18th century.
Sharp (1704) extended the Métius calculation taking the value to 72 decimal places and was correct up to the last figure.
John Machin (1704) calculated 100 decimal places all of which have proved to be correct.
Laguy (1719) was not so lucky. His calcuation of up to 127 decimal places has since been found lacking after the 112th place, and in 1794, Véga took the precision to 140 places (of which 136 have proved to be correct), followed immediately by Callet with 154 places (152 correct). 

1800/1900 
Various 
It was not until 1841 that Rutherford took the value to 208 decimal places but was quickly found to be in error to the last 56 when Dahse published his calculations in 1844 to a full 204 places, and Claussen (1847) to 250.
Not to be outdone, in 1853, Rutherford took his tally to 440 decimal places all of which have subsequently been found to be correct. He was finally outshone by William Shancks who in 1873 took the figure to 707 decimal places. 

20th Century 
Various 
The introduction of electronic calculators have taken all the fun out of the Pi calculations. William Shancks figure was found to be incorrect only after the 528th decimal place. The current record is held by Gregory & David Chudnorsky who in 1989 calculated Pi to an impresive 1,001,196,691 decimal places almost doubling the previous record 536,870,000 places set only in 1985 by Yasumara Kaneta. 
