To learn how to use Excel to do calculations, let’s say we wanted to create a new column that contains the value of the color (difference in magnitudes) u-g for each star.
First, click on the top cell in your new column and type a label. Next, click on the cell just below the label. Type the equals (=) sign. Next, click on the column for u in the same row. Type the minus (-) sign. Click on the column that contains the g value. The spreadsheet should look like it does below:
Hit Enter and the spreadsheet will calculate u-g for that cell.
Next, select all cells in the u-g column (except for the label). Click the Edit menu. Select Fill and then Down. The entire column will now have the u-g value for the star in its row.