Aside from the sister-in-law who lives in Michigan, it seems that the majority of the people wandering onto this blog are algebra students. At least I think they are algebra students. The reason I am not a retired architect instead of a retired bookseller is that my math abilities are comparable to my ability to fly. That is, largely a matter for my dreams. They could be physics or chemistry students for all I know, but the phrasing of their searches leads me to believe they are struggling with a math problem; and since algebra is the branch of mathematics I understand least, I assume that's the kind of math.
Anyway, these poor souls are doing Google searches for "missing factor" or some similar phrase, and Google obligingly directs them here. I imagine it can be quite frustrating to be desperately searching for the answer to a homework problem or help preparing for a test and suddenly find yourself looking at the ramblings of some old geezer.
For this I sincerely apologize. I hope the exam goes well, and that you do find an answer to your missing factor problem
If it is any help, the missing factor in my life has always been 9.