• Announcements: Today's lecture is remote asynchronous: please work through the short videos below in order, pausing if needed to solve exercises along the way, before I explain the solution on the video. Our next class, on Monday Feb 7, will be in person; so make sure you finish working through the videos below before that. Also, please remember that the mock homework (HW0) is due today, via Blackboard, by 11:59pm. As always, if you have any questions, please feel free to reach out by email.

• Video 1: Recap from last lecture, and combinations: Download file or watch below

• Video 2: Pascal's triangle and Pascal's relations: Download file or watch below

• Video 3: Binomial Theorem: Download file or watch below

• Video 4: Multinomial coefficients and Multinomial Theorem: Download file or watch below

• Video 5: Counting exercises: Download file or watch below

• Video 6: Walking around a grid (e.g., Manhattan): Download file or watch below

• Video 7: Number of positive/nonnegative integer solutions to equations: Download file or watch below