I believe there may be a potentially incorrect example in one of the prepswift videos, in the “Multiplication: The “Choice” Method” under the “data analysis foundation” section. The problem in question is the last one in the video. The problem states the answer is 639 because there is 1 possibility with no toppings but technically due to the 10 flavors there should be 10 possibilities with no toppings making the answer 630.
This has already been mentioned below the video.