PI

Pi (π), the sixteenth letter of the Greek alphabet, denotes an irrational number that is the ratio of the circumference of a circle to its diameter. Mathematical calculations of its value began in about 2000 B.C., the so-called Rhind papyrus figuring it at 3.16045. Archimedes had sharpened this to 3.1418 by 250 B.C., Ptolemy to 3.14166 by 150, the remarkable Chinese mathematician Tsu Ch’ung Chi to 3.141592920 (or 355/113) by A.D. 480. Sir Isaac Newton calculated π correctly to sixteen decimal places in 1665, and it had been resolved using manual means to 620 decimal places shortly after World War II. Calculators and computers have subsequently turned its solution into an exhibition of pedantry. Twenty years ago, π had been correctly resolved to 10 million places; Japanese mathematicians Kanada and Takahashi have since used a Hitachi SR8000 to calculate it to 206,158,430,000 places. This is π to 600 places:

3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679 8214808651 3282306647 0938446095 5058223172 5359408128 4811174502 8410270193 8521105559 6446229489 5493038196 4428810975 6659334461 2847564823 3786783165 2712019091 4564856692 3460348610 4543266482 1339360726 0249141273 7245870066 0631558817 4881520920 9628292540 9171536436 7892590360 0113305305 4882046652 1384146951 9415116094 3305727036 5759591953 0921861173 8193261179 3105118548 0744623799 6274956735 1885752724 8912279381 8301194912 9833673362 4406566430 8602139494 6395224737 1907021798 6094370277 0539217176 2931767523 8467481846 7669405132