The missing number is 5 inches.

Quick explanation

  • In the official Laws of the Game for soccer (Law 1 – The Field of Play), it states that all lines on the field must be the same width and “must not be more than 12 cm (5 ins).”
  • So the complete sentence is: “The lines on the field of play must be the same width, which must not be wider than 5 inches.”

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