L-B number is a number with distinct non-zero digits divisible by each of its digits e.g. 186432.

a. What is the largest LBN not containing the digit 1?
b. How many LBNs contain the digit 4?
c. Same for digit 5.
d. What is the largest LBN?

Provide your reasoning and/or program; solution by searching for answers on the web will be considered unfair…