Archimedes
Euclid
"Not as a decimal or fraction as there are an infinite number of digits." This is a common and useful answer. The *correct* answer is that PI is firstly an irrational number that cannot be calculated from any ratio (fraction). Secondly, PI is a transcendental number that, by the definition of "transcendental", cannot be exactly calculated. The nest you can do is to apply an infinite convergent series that becomes more and more accurate with more and more decimal places.
22/7 I think is the closest fraction you will get. By definition it is irrational, and cannot be written as fraction of integer numbers. There are a few fractions that are close approximates though. Pi cannot be technically written as a fraction. However, a fraction that is a close approximation of pi is 22/7.
You can either 1)You can divide out the fraction used for pi then multiply by the diameter or 2)Put the diameter over 1 then multiply across with the fraction used for pi.
main fraction:22/7 most accurate fraction:355/133
355/113 = 3.141593
Pi is infinite. It can't be converted into a accurate fraction. 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679 8214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196 4428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273 724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609...
Since pi is irrational, there is (by definition) no way to express it as an exact fraction. Even so, many people write it as 22/7, which is a fairly accurate representation. But it is not exact!
22/7
PI = 3.14159265... Most famous fraction is 22/7 = 3.142857... However better is 355/113 = 3.14159292... Ratty
most likely 2/7
The equivalency of Pi in a fraction is 22/7.
22/7 is fairly accurate to 2 decimal places: 3.14 and it the most commonly used one. 333/106 is accurate to the first 4 decimal places: 3.1415 355/113 is accurate to the first 6 decimal places: 3.141592
355/113, originally from China. It's value is 3.14159292035, accurate to 6 decimal places.
The most accurate calculation of pi is currently estimated to be around 31.4 trillion decimal places. This calculation was achieved using supercomputers and advanced mathematical algorithms. However, for most practical purposes, using pi to just a few decimal places (3.14159) is sufficient.
Archimedes