1. "Look, Dad," said Ben, holding out a piece of paper. "Our new number is one less than the square of Granny's age." Hamish thought a moment. "The four-figure number, you mean," he replied. "But if you add one to a third of it you get the square of my age. What about that?" What was the number?

Phone number 4860

Phone number 5040

Phone number 3090