I have an interesting challenge - I need to run a check on the following data in Excel:
| A - B - C - D |
|------|------|------|------|
| 36 |
I know it a little late to answer but I think this short video will help you a lot.
http://www.xlninja.com/2012/07/25/excel-choose-function-explained/
Essentially it is using the choose function. He explains it very well in the video so I'll let do it instead of typing 20 pages.
Another video of his explains how to use data validation to populate a drop down which you can select from a limited range.
http://www.xlninja.com/2012/08/13/excel-data-validation-using-dependent-lists/
You could combine the two and use the value in the drop down as your index to the choose function. While he did not show how to combine them, I'm sure you could figure it out as his videos are good. If you have trouble, let me know and I'll update my answer to show you.