Calculate PI number with given precision using Bailey–Borwein–Plouffe formula. Calculations are parallel thanks to PLINQ.
Project uses BigNumber class by Zimmermann Stephan.
Make sure that your IDE downloads missing NuGet packages for you.
I worked on MBP late 2013 running Windows on VM (it had access to 4 cores of my processor).
It took around 1 minute to compute PI with 40 000 decimal places (~60% faster than doing it without parallelization).
I used Bailey–Borwein–Plouffe formula to compute PI in hexadecimal system. Unfortunately converting it to decimal number is a little bit tricky because of lack advanced BigNumber library for .NET (even JavaScript has one). I needed arbitrary precision floating-point math with support for hex numbers. Finally I used BigInteger and BigNumber classes to achieve goal.