Carlos is arranging books on shelves. He has 56 novels and 16 autobiographies. Each shelf will have the same number of novels and autobiographies. If Carlos must place all of the books on shelves, what are the
possible numbers of shelves Carlos will use?

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?