To Do: Read the Solutions to Proof Quiz #9. Read them actively, as always. There are three proofs presented, and you only submitted one, so there’s something to learn there. And please read the second page with common errors, where I explain the most common error with surjectivity! (I decided to do solutions just text, not video this time.)

To Do: Take a look at the multiplication tables here, and collect as many patterns as you can. Just try to describe them.

To Do (IMPORTANT; NEW CONTENT): Watch my follow-up YouTube video on defining the integers modulo n (17:26). This is more practice with the formalism, and the work one needs to do to make sure integers mod n are well-defined.

To Do: Complete the exercise mentioned at 12:48 in the video. Hand in on canvas.