1."Look, Dad," said Harry, "that's John's new house number." Tom looked. "Yes, I know the house," he told the boy. "But what's that about the number?" "It's all there," Harry replied. "When you add the square of the first figure to the square of the other two figures, you get one less than the number. Isn't that something?" What was the number?

House number 561

House number 726

House number 382