I don't think it's impossible to do it (I think I could be around that but I should run some numbers before confirming that.. and no, I'm not homeless :)), but it's also not that easy to do the calculation: it's easy for rent and maybe other expenses (internet access, bills) but when you go to one-shot expenses like furnitures or cars etc.. I think there's not an agreed methodology on how to split them over the years (5 years ? 10?) so those could easily spoil the maths.