The problem of the week will return in the Spring 21 semester. We thank everyone who participated this Fall and we congratulate Yuqiao Huang, who is again an undisputed leader this semester (as he was in the Spring 2020) . For the winter break, we suggest reviewing all the problems from the Fall and working on the additional problems posted at the bottom of the provided solutions.

• Problem 7 Solved by Yuqiao Huang.

• Problem 6 Solved by Yuqiao Huang.

• Problem 5 Solved by Yuqiao Huang.

• Problem 4 Solved by Yuqiao Huang.

• Problem 3 Solved by Yuqiao Huang.

• Problem 2 Partial solutions received from Yuqiao Huang, Maxwell T Meyers, and Matthew Pressimone.

• Problem 1 Solved by John Giaccio and Yuqiao Huang.