Help with page numbering in Flash Paper prototype

Not sure how many remember what flash paper was, but it was a program that converted PDFs into a flash application.

So I am building it in AS3 (not the conversion process, but the viewer).

View it here

My question has to do with the zoom feature, well I guess the previous/next buttons as well.

The way the previous and next buttons work is they reference an array of Y values of where the next page is. The array looks like this:
0,800,1600,2400,3200…etc

This works fine, however, when I go to zoom those values are not accurate anymore more.

Whenever you Zoom up I up the scale by += 0.1
Whenever you Zoom down I down the scale by -= 0.1

In that process I need to update the Y Value array to match the new height of all the combined pages. How could I do that?