Convert column letter to number

Summary
Explanation
The first step is to construct a standard "A1" style reference using the column letter, by adding a "1" with concatenation:
B5&"1"
This results in a text string like "A1" which is passed into the INDIRECT function.
Next, the INDIRECT function transforms the text into a proper Excel reference and hands the result off to the COLUMN function.
Finally, the COLUMN function evaluates the reference and returns the column number for the reference.
Download 100+ Important Excel Functions
Get over 100 Excel Functions you should know in one handy PDF.