Sure, I can help you with that! You can use the

Code:

ASCII code function

in Excel to convert letters to numbers. Here are the steps:

1. Open your Excel spreadsheet and select the cell where you want to enter the formula.
2. Type the following formula into the cell:
   Code:

   =CODE(A1)-65

3. Replace "A1" with the cell reference of the letter you want to convert. For example, if you want to convert the letter "B" in cell B2, you would enter
   Code:

   =CODE(B2)-65

   .
4. Press Enter to apply the formula to the cell.
5. The result will be the corresponding number for the letter you entered. For example, if you entered "B", the result would be "1".
6. To convert multiple letters at once, simply drag the formula down to apply it to the other cells.

That's it! Your letters should now be converted to numbers in Excel.