Skip to content
the grown-up commonsPlay togetherBack to room

← Love, Fifteen, Thirty

Love, Fifteen, Thirty

Three short lessons for tennis watchers: reading the score, why a small edge on points becomes a big edge on matches, and why nobody is sure where 15-30-40 came from.

Spark & Whetstone · sparkwhetstone.org/learn/love-fifteen-thirty · CC BY-NC-SA 4.0. Answers are at the end, so you can try each question first.

Lesson 1. Reading the score

A tennis game counts points as love (0), 15, 30, 40, then game. At 40-all the score is "deuce", and a player must then win two points in a row: one gives "advantage", the next wins the game.

Games make sets (first to six, by two, often with a tiebreak at 6-6), and sets make the match.

Question. The score is advantage server and the receiver wins the next point. What is the score now?

  1. Game to the receiver
  2. Deuce
  3. 40-30

Say it back. In your own words: why can a game at deuce go on for a long time?

Lesson 2. Edges compound

A player who wins 55% of points wins about 62% of games, because a game needs several points and a longer run lets the better player’s edge show.

The same happens again for sets and matches. A player winning just 51% of points wins about 63% of best-of-five matches in a simple model where every point has the same chance.

Question. Which format gives the stronger player the bigger chance of winning?

  1. Best of five sets
  2. Best of three sets
  3. A single tiebreak

Say it back. In your own words: how does a small edge on points become a big edge on matches?

Lesson 3. Where 15-30-40 came from

Nobody knows for sure. One popular story says scores were kept on a clock face, moving the hand a quarter at a time: 15, 30, 45, then 60 for the game, with 45 later shortened to 40. Another links the counts to an older French handball game.

The surviving sources do not settle it, so the honest answer is that the origin is unsettled. The maths of the score does not depend on it.

Question. How should a careful fan describe the clock-face story?

  1. As made up and impossible
  2. As one plausible explanation that the sources do not confirm
  3. As proven history, settled by records from the courts of the time

Say it back. In your own words: why is "it fits the numbers" not the same as "it is how it happened"?

At the table: Keep the score on the sofa

Players: Two or more, ages 6 and up. You'll need: A tennis match on TV or a backyard rally, paper.

  1. One person calls the score aloud after every point: love, 15, 30, 40, deuce, advantage.
  2. Another keeps a tally of who won each point.
  3. At the end of a game, count the points each player won and check them against the calls.
  4. Talk about a game where one player won more points but lost the game.

Answers

  1. Deuce — Losing the advantage point brings the game back to deuce; a player still needs two points in a row.
  2. Best of five sets — The longest contest lets a small advantage add up the most, so best of five favours the stronger player more than shorter formats.
  3. As one plausible explanation that the sources do not confirm — The clock-face idea fits the numbers, but fitting is not proof; without a source that confirms it, it stays a plausible story.