The exact answer was 514,414. To the nearest 10,000, this (according to me) is 510,000. The instruction was to accept anything between 500,000 and 520,000. You might think that a fraction over 1% one way, and just under 3% the other, is not excessively generous, as leeway goes; in fact it's not even fair. But it's more generous than "to the nearest 10,000".
520,000 I can understand, as it's not that much further away than 510,000 (which, according to me, is the correct answer, adhering strictly to the wording of the question). But 500,000 is almost three times further away!
If the question had said "to within 10,000", any answer between 504,414 and 524,414 should have been accepted. This might have been a fairer way of doing it - even if the leeway (a little less than 2% either way) is still less than generous.
And on the subject of pedantry ... I'm sorry, but I don't think this ("viz NOT including Wigan ... etc.") is a correct use of the abbreviation "viz".
Viz is short for the latin word videlicet, which means (according to Google Translate) 'namely'. The New Oxford Dictionary of English (first edition, 1998, reissued with corrections etc. 2001) gives the same meaning, adding "in other words (used especially to introduce a gloss or an explanation); the first music reproducing media, viz. the music box and the player piano."
A gloss, by the way, is (in this context) "a translation or explanation of a word or phrase".
If you replace "viz." with "namely" in the above example, it makes perfect sense. If you do the same with the question about the population of Manchester, I don't think it does. For a start, "not including ... " is a different part of speech from "the City of Manchester" - it's an adverb, not a noun.
Surely "i.e." would be better?
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