Thanks a lot for your inputs Pamfafoofle (great name btw!).
The prosperity calculation was indeed wrong. Since I based this calculator off the Pharaoh worksheet, I didn't bother checking whether the two games calculate prosperity differently (which of course they do...Pharaoh uses population while Caesar III uses number of houses).
To fix it, I've added Mrgd housing inputs for all levels up to Medium Insulae and changed the formulas to compute using houses rather than population. I've also added a new column to report the total number of houses. This simplifies the formulas to some extent.
As for the required number of raw material and workshop buildings, the calculation was correct but the decimal components were not being shown. 672 units of pottery requires 1.4 workshops which Excel was showing as 1 due to formatting issues. I've now changed that to show two decimal places for cartloads, farms, raw material and workshop requirements.
A case could be made for rounding up to the next integer value but I can imagine some situations where this may not be desirable. For instance, 24 Large Insulae + 6 Grand Insulae require 7.09 non-northern wheat farms. One may wish to simply forgo production of the additional 9 units to save on the extra farm (and food distribution would probably be OK). So I think leaving this choice to the user is fine.
Version 1.1 of the worksheet can be downloaded using
this link. I'd appreciate it if you could perform some more tests.
I'm glad to see interest in an export calculator. I'll start working on a version 1.2 to include that as well.[This message has been edited by SiddharthP (edited 09-23-2020 @ 01:05 PM).]