The object of this exercise is to practice "algorithmic thinking."
You have three tasks, with some very minimal tests set up. Write some more tests if you would like to refine your code further.
Treat this session as a mob programming session.
Before you write any actual code, make sure the students think through the strategy they are going to use. (Perhaps write five or six comments in the method body as their strategy.)
Questions 1 and 2 are intended to let you practice various string, array, integer and float methods.
Question 2 will probably use a while loop, but maybe you could research recursion!
Question 3 should let you practice navigating through hashes and arrays.