4.1-4.2, due on January 25

1. The modulo phrasing is very hard for me to work with. I think after the lecture and the homework it will probably get clearer, but it takes me a while to look at some sort of modulo and know what it actually looks like in n|(x-y). And then it takes me a little while to figure out what that means! Hopefully it will become more natural with practice.

2. I think I've heard of modulations (?) before in another class. I think I remember one of my past professors saying that it would be really good to know about for future math classes. Is that true?