What is the word?
Between your house and her house, you have to cross
7 bridges, and as it goes in the land of make believe, there is a troll
under every bridge! Each troll, quite rightly, insists that you pay a troll
toll. Before you can cross their bridge, you have to give them half of
the cakes you are carrying, but as they are kind trolls, they each give
you back a single cake.
How many cakes do you have to leave home with to make sure that you arrive at Grandma's with exactly 2 cakes?