Suppose a frog is on the side of a one-meter-wide river and hops across. The first jump is a 1/2 meter hop, then a 1/4 meter hop, then an 1/8 meter hop, and so on. How many hops will it have to take to reach the other side?

It takes an infinite number of hops! The frog will never fully reach the other side in a finite number of hops.