Sally likes 225 but not 224; she likes 900 but not 800; she likes 144 but not 145. which does she like - 1600 or 1700?

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