This will calculate ALL prime numbers up to a certain number which you can choose, just click the flag, type in your number, wait a few seconds, and then it will have the primes. The best part about this is that it does it incredibly fast, because of the Run Without Screen Refresh option. Beware of typing in numbers that are too large, because this will make it laggy and hard to run.
I give myself credit, because I randomly clicked the Create List button and then suddenly discovered how to use lists and how they could help me here.
