You have received the direct answers to your question. You run the Solver for each case you want to address. However, depending on your situation, you may find that using a single file format for each one and running the Solver within each file using different data is a way to keep things smaller per instance and may be more convenient for you. I'm doing this with stock trading models over hundreds of stocks and "summarize" the results in one Workbook/Worksheet - which also controls running Solver in each file (as in over night). In a sense, this is similar to trading memory for compute time in some applications. It isn't likely to use more memory, in fact perhaps less memory at any instant. But it probably uses a bit more compute wsll clock time to account for opening and closing files.