PINY + THE ELDER"My favorite number is PINY in the above equation." (Every letter is consistent throughout, and no number is represented by more than one letter.)
One day when he said this, a listener said, "My favorite number is 1537, a number such that its first two digits add up to an even number, and also such that each of the two middle numbers is between the first and last numbers. How many of these two conditions does your number meet?"
Upon hearing the answer to this, the follower knew what Piny the Elder's favorite number was. What was it?