Well the answer to this is very interesting and very easy in many ways I can go on about this and talk about how easy this question is I will answer it by looking at the questions I think the answer is included in this small piece
Creating several tables within the same worksheet or spreadsheet. The computer assumes an erroneous association between these tables. So Ray ought to avoid doing that
Merging Cells. This usually creates problems when its time for analysis.
Entering multiple data into one cell. For example, stating 1 MB (One Mercedes Benz) and 3 LX (three Lexus cars). If you try summing both cells, you'd realise that it will errors.
Solution:
Separate tables into difference worksheets and reference them where necessary. Excel can hold at least 255 worksheets. I doubt that you'd need that much.
To check that you don't have any merged cells, first, save a copy of the master file then modify one the copies by highlighting the affected worksheets then use the unmerge function to remove any merged formatting. Thereafter, trace all relevant cells to ensure data consistency.
With regard to different kinds of data, ensure you enter them in separate cells. That way Excel will understand better what you are trying to process.