00:01
For problem 41, we're working to arrange books, and we have eat math books and three chemistry books.
00:12
These books must be kept together.
00:15
However, they all go on the same shelf at the end of the day.
00:20
So let's figure out how many arrangements these math books can be in.
00:24
Well, there's eight books, and those must fill eight slots.
00:29
So in the first slot, there's eight options.
00:31
The second slot, there's seven options, and there's six options, and so on as the books get filled in.
00:36
This comes out to 8 factorial, which will take 8 and multiply it by every number decreasing after it...