Packing Primes, make-up post

1. Difficult: I'm afraid I have to admit that the majority of Dr. Friedberg's lecture made very little sense to me. If it had gone a little slower, I probably could have gotten it. But by the time I wrapped my mind around one concept he had jumped past two or three more concepts. The thing that was most difficult for me to understand was the example he gave in the beginning with the ATM. I know he was trying to tell us how primes can be used in a real-world application, but I just got lost. Something about taking a prime, and multiplying it by 541 and then finding the remainder of the division of the prime? What the what? I was so lost.
2. Reflective: However, I really enjoyed his sand-metaphor. The idea of-- if you blow grains of sand up so that they're huge, then they don't fit together very well at all. But if you have small grains of sand, you can pack MILLIONS of them into a bucket with no problem at all! This metaphor was probably the thing that really made it so I knew what he was talking about. I loved it!