23 is a prime number.
When 23 or more people are in the same room there is a better than evens chance that at least two of them share the same birthday. As the average class size in British schools is larger than 23, more than half the classes in Britain have two pupils with the same birthday.
Two different ways of making 23 with a pattern of dots. Can any number be made with this type of pattern?
'Twenty-three, skidoo!' is an American catch phrase from the beginning of the century. It may have come from the stage play of Charles Dickens's A Tale of Two Cities where an old woman counts the victims being executed on the guillotine. As she speaks 'Twenty-three!' the hero Sydney Carton is beheaded in the last act. Henry Miller's serious dramatisation of the story was parodied by Broadway comedians and became 'Twenty-three, skidoo!'.