So I'm sitting here doing cost estimations for Seismic Crews. A few thousand people, food, lodging, production estimations, etc. It's really very complicated to work out, but it's possible, because I have Excel, Telephones, Email, etc. I can get quotes from people quickly, get operational estimates from experts, and plug all the numbers into a model to work out a cost.
Now I'm imagining big military campaigns of the ancient Roman world. According to some of the ancient sources, armies could number upwards of 80,000 soldiers, who had to be equipped, fed, sheltered, etc. for open-ended campaigns that could span years in unknown circumstances. The cost model/accounting would have to be done on paper, without double-entry bookkeeping. It would be done in Roman Numerals, where the person would have to figure they had MMMDMCDLVIII available loaves of bread per granary available to feed MLCVIII or whatever soldiers per unit and would have to do that crappy math. Finally, they'd have to copy their records/projections on many pieces of paper so that they could send it out by horse to all the important personnel who needed the information.
How the hell do you manage such a massive operation in real time under those conditions? It's hard enough for me with modern tools. It's hard to imagine under Roman conditions.