Discrete Mathematics, Mathematics, Combinatorics.
guys to get 41. Odd: There would be 45 choices but theres 5 bad guys (11,33,55,77,99) so 45 minus 5 = 40 choices. Ok…interesting. Notice that you can start to build the answer for the next number of digits using the answer from the previous number of digits. That’s recursion. Recursion: En = # of