functions in pseudocode

Question

I am still working on the ISBN project and now I want to split my pseudocde into functions and or procedures... I will just identuify for you the things that I thought needed to be in functions of their own coz i had done everything on main... I have to validate the ISBN( i already posted that part of the pseudocode) then I need to Convert the ISBN10 to ISBN13(that was the last part we worked on) but I feel as much as I included the odd and even number checking in the whole converting "function" that there shud b a seperate function that will determine if a digit is even or odd...then I need to have a function that adds a hyphen on the ISBN 13...I should then call all these functions on main.
You dont have to do all of them though I just need an idea of what is expected from me. Your help will b appreciated, Thanks.