The following puzzle is from a Scottish mathematical competition and has been posed at the Jordanhill school in Glasgow: A shop sells letter signs, and the price of every letter is an integer number of pennies.

  • The letters of the word ONE cost 1 pound sterling.
  • The letters of the word TWO cost 2 pound sterling.
  • The letters of the word FOUR cost 4 pound sterling.
  • The letters of the word ELEVEN cost 11 pound sterling.

What's the price of the letters of the word TWELVE?

  • 1
    $\begingroup$ This is very close to a pure maths problem IMO. $\endgroup$ – boboquack Mar 30 '17 at 9:05
  • $\begingroup$ @boboquack I think the very cute answer justifies the mathiness! $\endgroup$ – Mike Earnest Mar 30 '17 at 15:15
  • $\begingroup$ Has a correct answer been given? If so, please don't forget to $\color{green}{\checkmark \small\text{Accept}}$ it :) $\endgroup$ – Rubio Apr 3 '17 at 18:07



Which is:

ELEVEN-ONE+TWO (because the O's cancel out and rearranging letters doesn't do anything)

Which is:



FOUR=£4 is a red herring

  • $\begingroup$ Heh, so it again equals the number? I wonder how many other numbers this applies for... $\endgroup$ – Weckar E. Mar 30 '17 at 10:09
  • $\begingroup$ @Weckar I think this is just a one-off, because ELEVEN PLUS TWO = TWELVE PLUS ONE in letters as well as numbers - I can't find a similar thing for other numbers. $\endgroup$ – boboquack Mar 30 '17 at 20:05
  • $\begingroup$ It applies for SIX. $\endgroup$ – Ian MacDonald Mar 31 '17 at 1:35
  • $\begingroup$ @Ian how so? Is it something to do with the teens? $\endgroup$ – boboquack Mar 31 '17 at 2:06

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