If you have 20 players in a tournament with single elimination, you will have to play 19 games...
There is no timing associated with a pool tournament. How long a pool game lasts depends upon the types of games being played and the skill of the players.
The amount of players in a poker tournament varies from tournament to tournament. For example the poker games played in Vegas accommodate two to approximately sixteen people.
Assuming that a knock out is a single elimination tournament, where each player/team plays until they lose, there are 38 games. Only one team will not lose.
There would be 21 games.
ItS 21 games
10 games From concerned reader: if I am reading the question correctly, the answer of 10 games submitted is not accurate. However, let me clarify the question first. I believe that we are asking how many games must be played in total to determine one, and only one, winner of the entire tournament. Given that this is the correct interpretation of the question, the correct answer is that 19 games must be played to determine a singular winner of the tournament.
The first international chess tournament was played in 1851 and won by Adolph Anderssen. Prior to that there had been games between players from different countries, but that was the first tournament.