Big Pi by Zeda Thomas This is a set of BASIC programs to calculate pi to arbitrary precision. How to use: Send all of the programs to your calculator On the homescreen, do something like: 20:prgmBIGPI This computes PI to 20 digits (it outputs more, but those may be inaccurate). Read L1 as 5-digit chunks of the expansion of pi! The last chunk will probably be off in the last few digits. This takes can take a LONG time! It takes a few minutes to evaluate 100 digits. Tweaks: If you open up BIGPI in the editor, you will see a line that looks like: 5->I This determines the size of the chunks of the digits. Increasing this will speed up the calculation, but it can cause errors due to floating-point precision. For example, using a size of 10 digits caused the result to be off after about 40 digits. I haven't tested it enough, but a value of 8 should be safe while speeding up calculation by 60%. 9 *might* be safe, but I don't know.