Answer:
The number of cardinals varies as older cardinals pass away or new cardinals are appointed. There are currently about 180 cardinals world wide but only 120 of those are eligible to participate in a papal conclave to elect a new pope. Once a man reaches 80 years of age he remains a cardinal but is unable to vote. The pope usually will appoint new cardinals to fill the positions held when a cardinal retires or dies so as to keep the number of electors about 120.