red and green flag to start and stop. this starts at N then randdomly chooses a number between 0 and N then chooses a random number between that number and zero. this repeats and the number of times it repeats is stored as "average" N can be changes using the slider. changing it while the simulation is running will yield inaccurate results. "how many times" is how many times the simulation will repeat. higher will lead to more accurate results.
