Can you really lose 15 pounds a week by doing this?

So I know what you're probaly gonna say "that's too unhealthy blah blah blah" but no, I'm not really aiming for that much is so little time, but I calculated that. So what I did was this 900 calories a day times 7= 6300(that's how much I normally eat. don't blame me cuz my mom just buys these low calorie asian foods or 1000 calories a day) and then I add up how many claories I burn a week which is 6500 and then I subtracted that to 200. after that I dived 200 by 3000 and I came up with 15 pounds. So can you really lose that much or did I just calculate that wrong because that seems very unrealistic