arrays in pseudocode

Question

Im still working on the ISBN project and now Ive validated it, the next step is to convert a 10-digit ISBN to a 13-digit ISBN. I got the formular for that now I want to create procedural pseudocode showing the steps. I was thinking of using an array to store the 10 digit array because inorder to convert it I have to divide the digits somehow coz the formular wants us to add the digits in the even positions then multiply them by 3, add that to the sum of the digits in the odd positions...and so on. So if this was a normal c# problem I'd store the ISBN in a file each digit seperated by a character e.g 0#2#3#0#4#5#6#4#7#9 so that I can use a streamreader to store the odd numbers alone and the even numbers alone in seperate arrays... I'll stop here for now in case thers things that aren't clear. Thanks