My girlfriend wanted to change the color scheme in her bedroom. She knew the color she wanted but wasn’t sure how much wall covering she needed but her friend down the lane had done something similar recently and the rooms were about the same size.
“Sarah” she asked, “Can you remember the number of rolls of wall covering it took you to decorate your room?”
“Twelve” she replied.
My girlfriend duly bought the twelve rolls of wall covering, finished the job and found that she had three rolls remaining. She phoned Sarah and told her this to which she replied, “Oh, I’m not surprised, so did I!”