Consider numbers as
X - 0 (No zeros for this digit)
XX - 9(Total 9 times zero will appear)
XXX - 90(Zero at tens place)+90(Zero at units place) - 1(common case when 0 apears both at tens and units place) = 179
1000 = 3
I had made the same mistake in challenge 1 what you have done above.
Since this question is asking how many times 0 is listed we have to account for each 0 that appears.
X00 has 2 zeros. If you remove the common case you will be counting this number only once, but we are not supposed to count the number. We are supposed to count the number zeroes.
X00 as 2 zeros and should be counted twice. 192 should be the correct answer.
I'm crossing the bridge.........