A man goes to his neighbor for advice on redecorating his living room.

Their houses were in a new subdivision and were identical to each other inside and out. So this man figures his neighbor, Jim, would be helpful for advice on how much wallpaper to buy for his living room.
He goes to his neighbor's house and greets him.
"Jim, I've been thinking about changing the wallpaper in my living room, and I know you just changed your own living room's wallpaper recently. Now tell me, Jim; how many rolls of wallpaper did you buy to do it?"
Jim replies to the man that he bought 10 rolls of wallpaper for the job, and so he thanks him and goes out to buy them.

A couple of days later, the man comes back, furious. He had put up the new wallpaper and found he still had a large amount left over.
"Hey, Jim! You told me to get 10 rolls to cover the living room. Now I've done it, and there's still 4 rolls left over!"
"What a coincidence! So did I!"