Where does it come from?: Tennis scoring is notoriously confusing and appears to defy all mathematical logic.
The system used at Wimbledon and throughout the modern game is believed to have its roots in medieval France.
The clock face: The most widely accepted theory suggests that early players used large clock faces to track the score.
Each quarter-movement of the minute hand represented a point: 15, 30, and 45, with 60 signalling a game win.
Why did 45 become 40?: In French, 45 is 'quarante-cinq' (three syllables), while 40 is simply 'quarante' (two syllables).
