Question 5
In increasing order, list the positive integers containing only odd digits: $1,3,5,7,9,11,13,15,17,19,31,33,35,37,39,51,53,55,\ldots$. (a) Find the 2022nd term. (b) Find the smallest term whose digit sum is 2022. (c) Find the sum of all terms not exceeding 2022.