Peter, Paul and Mary have between them 282 marbles. Though of the three friends, it is Peter who has the most marbles, he is the one with the fewest silver marbles, just the square root of the number of all his marbles. On the other hand, Mary, who has the fewest marbles, is the one with the largest number of silver marbles, precisely one seventh of her marbles. How many silver marbles does Paul have?
