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A Sixty-Four Player Tournament (illustration)
FILE No.94Unsolved

A Sixty-Four Player Tournament

Difficulty ★☆☆about 3 minEveryday MysteryChange of viewpointTournaments
A 64-player single-elimination tournament, no draws. How many matches in total?

Case Record

The town chess club held a 64-player knockout tournament. Lose once and you are out. There are no draws. Matches continue until a champion is decided.

The organizer asked the scorekeeper how many matches there would be. The scorekeeper began adding: "Round 1 is 32 matches, round 2 is 16 ...".

Your question

How many matches are played in total until the champion is decided?

Case Files

Evidence

Diagram

Check by addingRoundMatchesRound 132Round 216Round 38Round 44Semifinals2Final132+16+8+4+2+1 = 63 matches.
Diagram

Timeline

  1. A chess club knockout is played.

Hints

If you get stuck, open the hints one at a time, in order.

Open hint 1

How many players does one match eliminate?

Open hint 2

How many players are left at the end?

Open hint 3

How are matches related to eliminated players?

Solve It

Your question

How many matches are played in total until the champion is decided?

Choose the answer closest to the truth.

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The Truth

63

The answer is: 63.

Every match eliminates exactly one player. Everyone except the champion (63 players) must lose exactly once, so there are 63 matches.

Adding up the rounds, 32 + 16 + 8 + 4 + 2 + 1 = 63, gives the same result.

Count the losersEach match has exactly one loserEveryone but the champion loses once: 63 playersMatches = 63
Diagram of the solution

Key Points

  • Matches = players eliminated
  • One player remains, so 63 are eliminated
  • Count losers instead of adding rounds

Why people get fooled

Adding round by round hides the much simpler way of looking at it.

Similar tricks

  • The change-of-viewpoint type
  • The add-the-rounds type

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