let's count from 0 to 999
0, 1, 2, 3, ooh, look, there are 2 odd numbers, 4, 5, look another one, 6, 7, another!
we can see that every time you count from 0 to 999, at least 2 odd numbers show up
so answer is 1 time (because if 2 odd numbers or 20 odd numbers show up, it's still at least 2 odd numbers)
I think you really want to know how many times a pair off numbers occur together
like 33, 313 or 333, but not 31
that is interesting
in the first 10's 11 is only one
in each odd 10, in the 100's reigon, there is only 1 pair of odds
so 11, 33, 55, 66, 77, 99 or 6 pairs in the pre-100's zone
in the 100's zone, we have 101, 110-119, 121, 131, 141, 151, 161, 171, 181, 191 or 19 numbers with pairs of odds
in 200's, it's the same as pre-100's, 6 pairs
in the 300's zone, it's like 100's so 19 pairs
in the 400 zone, it's like 200's, 6 pairs
in 500's zone, it's like 100's, so 19 pairs
in the 600 zone, it's like 200's, 6 pairs
in 700's zone, it's like 100's, so 19 pairs
in the 800 zone, it's like 200's, 6 pairs
in 900's zone, it's like 100's, so 19 pairs
so a total of 6+19+6+19+6+19+6+19+6+19=125 pairs of odds
. Let x be the missing number.