Find the limit (picture below)

Can anyone me with 32,33,36,37,and 40.

What is not true about kl and mn? what is mn? (show )

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236