How's project 4 coming?

A note about primes:
	Large primes are used for RSA
	If you have a list of primes up to sqrt(v), you can efficiently check v

Suppose we want to calculate the "greenness" of a picture
	Let's compare two methods:
		1.  Keep global values
		2.  Keep local values, and add to the global values at the end
	We can use the second option because counts are independent

Time for each, and the "time" command

A note about project 5:
	We want a given number of primes, so we're searching toward an unknown limit
	If we knew the limit, we could work the other direction
		Sieve of Eratosthenes