MHB What are some interesting approximations of pi?

AI Thread Summary
The discussion highlights various interesting approximations of pi, including the well-known $\frac{22}{7}$ and $\frac{355}{113}$, which accurately represents pi to six decimal places. An intriguing approximation mentioned is the sum of two surds, $\sqrt{2} + \sqrt{3}$. A mnemonic for remembering pi is noted: "May I have a large container of coffee," where the letter count corresponds to the digits of pi. Additionally, the thread references a collection of unique approximations and celebrates a specific "Wagon Wheel Approximation of Pi" featured on Pi Day. The conversation invites further contributions on interesting observations related to pi.
kaliprasad
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we know a couple of approximate values of $\pi$ mostly $\frac{22}{7}$ and $\frac{355}{133}$ but one I found (from the net )interesting was sum of 2 surds $\sqrt{2} + \sqrt{3}$.if anyone is aware of other of interesting observation kindly let me know.
 
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Not an approximation but a mnemonic: "May I have a large container of coffee". The number of letters in each word: 3.1415926.
 
There is a collection of weird and wonderful approximations for pi here. My favourite is the approximation $\frac{355}{113}$, which gives the first six decimal digits of $\pi$ correctly, even though the numerator and denominator of the fraction have only three digits. The reason for that is that the following term in the continued fraction expansion of $\pi$ is the large number 292.
 
pi - log(23.141) = .000013282...
 
Seemingly by some mathematical coincidence, a hexagon of sides 2,2,7,7, 11, and 11 can be inscribed in a circle of radius 7. The other day I saw a math problem on line, which they said came from a Polish Olympiad, where you compute the length x of the 3rd side which is the same as the radius, so that the sides of length 2,x, and 11 are inscribed on the arc of a semi-circle. The law of cosines applied twice gives the answer for x of exactly 7, but the arithmetic is so complex that the...
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