I took both Math 180 and Math 61 with Professor Butler. He is the best Math teacher I have had at UCLA. Most of the Math classes he teaches (3B, 61 and 180) all have similar material, which he LOVES. The guy honestly loves his math. He does a wonderful job of using fun/quirky examples in class and his class is always uplifting. He does a great job of preparing materials for students to study from. Use the lecture notes that he posts online. His classes were challenging, but he makes it easy to follow, because he is so patient with students and is willing to explain something 100 different ways until his students get it. He always had very convenient office hours(and lots of them) and he's extremely helpful. His homeworks(especially the ones he makes himself) can be hard, but go to office hours and it will help a ton. I wish I could take more math classes with him, but sadly, I think it's over. Honestly though, I chose to take 180, because he was such a good professor. I would highly recommend this professor for any level of class.