Kenny has gone to a lecture by Jenny, a famous mathematician. Kenny tells Lenny that Jenny handed everyone at the lecture 2 cards, one containing a 5-digit prime, and the other containing a 5-digit square. All of the cards held different numbers.
Then she asked everyone to add their 2 numbers, and amazingly they all got the same sum. Kenny says it's lucky that Lenny didn't attend, because then the trick would have been impossible.