You can calculate it from the DOM and the %MAC using the bottom right hand bit of the load sheet.

There's only one exam question we know of like this.
Q. Given a DOM of 35,000kg and a CG of 14%MAC determine the Dry Operating Index.
A. Enter from the left or right with 35,000kg, go straight across to the 14%MAC line, read down to a DOI of 40.