Cathy, a blonde decided to redecorate her bedroom. She wasn't sure how many rolls of wallpaper she would need, but she knew that her blonde friend, Bambi, from next door had recently done the same job and the two rooms were identical in size. So she went next door to talk to her friend.
"Bambi," she said, "how many rolls of wallpaper did you buy for your bedroom?"
"Ten," answered Bambi.
So Cathy bought the ten rolls of paper and did the job, but she had two rolls leftover. She went next door to talk to her friend about it.
"Bambi," she said. "I bought ten rolls of wallpaper for the bedroom, but I've got two left over!"
"Yes," said Bambi. "So did I."