A positive multiple of 11 is good if it does not contain any

Question

even digits in its decimal representation.
(a) Find the number of good integers less than 1000.
(b) Determine the largest such good integer.
(c) Fix b ≥ 2 an even integer. Find the number of positive integers less
than b
3 which are divisible by b+ 1 and do not contain any even digits
in their base b representation. (This is the natural generalization of
part (a) with 10 replaced by b.)

Answer 1

11,33,55,77,99,121,319,517,539,...,979