Geometric sums and series.

64 players enter a tennis tournament. When a player loses a match the player drops out, the winners go onto the next round.

Find as many different methods as you can to determine the number of matches played.

I did it using $\displaystyle Sum6=(32(.5^{6}-1))/(.5-1)$

which equal 63 which is right... But I got n=6 by finding that there are 6 rounds by going - 64/2=32 32/2=16 etc.

What is the correct way to solve this say if there was 10, 000 rounds and you didnt want to waste time. thank you.