10 .
Somewhere earlier on we mentioned Bletchley Park: the HQ of the World War 2 codebreaking operation which cracked the Nazis' electromechanical ENIGMA code ~ and probably served to shorten that war by a couple of years, once our Intelligence were able to decrypt enemy messages and work around their troop movements etc.
Unfortunately for our present purposes, even if we ignore repeated letters, we cannot manage BLETCHLEY PARK using a mere two hands'-worth of cipher symbols ...
... but MILTON KEYNES (the nearest major place; a 'new town') is wonderfully obliging, since only 2 letters in the 12 are repeats. Let's code it as 657483 920321.
By very happy coincidence, MILTON KEYNES is full of interesting potential letter combinations; so for our very final number-coding Question, you will get to know this particular temporary code rather well (unlike in an middle school exam, where you handle a fresh one every couple of moments). But the added dimension here is that only ONE of these word-lists contains a slight mis-spelling; everything else is fine. So, as in real life, you are concentrating on what the 'clear' is saying, just as much as on the immediate mechanics of decyphering.
Which group contains the mis-spelt word?
26845837211 ; 566231540 ; 53187234 ; 9578483321 ; 938445214 ; 7514721170
6514889 ; 6851423 ; 6883754 ; 68384830 ; 651472482 ; 6874233211
101426 ; 1689570 ; 12654832 ; 186245621 ; 123154512 ; 18726354521
4831571 ; 4857241 ; 298386514 ; 4231583 ; 48923516 ; 456272113211
As it happens, in Answer 2, 0 was drafted-in to stand for H and 1 for L; 6 was not used at all