Imagine you have a dear relative who is a Sudoku nut. You want to buy this dear relative a gift which acknowledges this addiction, but, really, you think it is all a joke. You don't want to hurt their feelings, but at the same time, you do want to poke some gentle fun at them....give them this as a gift and a little smile will light their face whenever they pull it out to indulge in a little mental self abuse. Maybe that dear relative is you. By the way, Sudoku means "single number". Not the attention-grabber we might have hoped for.