Answer:
274560
Explanation:
We can "choose" one of the 66 athletes for the gold medal. That athlete can't win any other medals, so there are 65 athletes left.
We can then "choose" one of the 65 athletes left for the silver medal. That athlete can't win any other medals, so there are 64 athletes left.
We can then "choose" one of the 64 athletes left for the bronze medal.
That leaves us with 66 possible choices * 65 possible choices * 64 possible choices=274560 possible choices