Which of the following has a terminating decimal expansion?

One dividing a positive integer n by 9, we get 7 as remainder. What will be the remainder if (3n – 1) is divided by 9?

Show that any number of the form 4ⁿ, n ∈ N can never end with the digit 0.

The HCF of two numbers is 27 and their LCM is 162. If one of the number is 81, find the other.