Journalist's Arithmetic

37 - 19 = 20

That was affirmed several times by a BBC announcer reporting on the recent selection of candidates for the post of Conservative leader. One candidate's vote increased from 19 in the first round to 37 in the second and was reported to have increased by 20.

 After giving the figure the announcer paused for thought, repeated the figures 37 and 19 and said. 'that's right 20' so the error was not a momentary aberration.