Error In Mini-Question
As I was working on Workout 1A I noticed an error in the problem in Part 3. The question rounds 81/121 to 2/3 and multiplies 12x2/3 to get 8 pages. However, 81/121 is slightly more than 2/3, so when multiplying you'll get slightly more than 8. As Prof. Loh said, this will translate to 1 extra piece of paper.
Thanks so much for this comment! This fix has been made now.