Seen in a Mexican restaurant: fajita meal for three, $36. For four, $48. For five, $60. They then offer the helpful suggestion that if your group has nine people, you could order the fajita meal for four and the fajita meal for five, and you’d be set. Of course this is exactly the same as saying that the fajita meal is $12 per person, minimum of three people, since any integer that’s at least three can be written as a sum of threes, fours, and fives.