Column with Ratio of 2 other Columns?

Hi,

I'd like to set up a column tracking the ratio of size to #pages. My ideal format would be #ratio = (size*100)/(#pages+1).

The +1 is to avoid division by zero bugs when #pages is unknown.

I've looked in the manual, but the only ratios mentioned are aspect ratios.

I've looked in this thread: https://www.mobileread.com/forums/sh...t=column+ratio

And wrote this into "Template," but just get TEMPLATE ERROR

program: divide(field("size"),("#pages"+1));

So, uh, how should users build columns as ratios?