At one of my interviews I got killed with that question. I mean literally killed. My interviewer goes, "So, where have you applied?" I tell him three schools and about a second later he says, "Ok. Where else??" I give two more and he says, " You sure there are no others?" I gave him the 2 others and he stopped questioning me as if he knew that those were the only 7 schools that I applied to. I was so freaked out after that and I felt like that was going to be the reason I wasn't going to get accepted. I thought that he would think I'm a liar, but hey I still got in.
I think you should just really be honest and give at least 7/8 of the schools you applied to if you are asked to. BTW, he also asked me at which schools have I interviewed.
They do not know where you have applied for a fact! The box on the pink AADSAS sheet only says the name of the school where it is being sent. However, they can take an educated guess on the number of schools you applied to judging by your stats.
I had an 18/18 and 3.4 GPA so they knew it was at least 7/8. No way in hell did I apply to only 3 like I said orginally.