Plus Advent Calendar Door #20: Party problems
It's time to get out those party invitations! Trouble is, your sister doesn't get on with your boyfriend, your boyfriend doesn't like your best mate, and your best mate's just broken up with your cousin. Who do you invite? Find out why the answer could win you a million dollars! And for a slightly easier question, can you make sure that no two people you've invited have the same number of friends?
