Help Solve, This value must be a interger

You probably need a subscript i on InterStorey_Deflection.

In general, you should upload a Mathcad file, rather than just an image, to make it easier to identify the problem.

Alan

I too agree that you should upload the Mathcad sheet, to allow us to help you better.

It seems that you missed to type an index i at the InterStorey_Deflection array, it should be:

                        ^

Success!
Luc