Looking ahead, you’d often like to know how the bottom line would look with an 8% increase in sales or across-the-board salary increases of 4%. Here’s the formula for increasing numbers by a certain percentage: =C10*(1+8%). In this example, C10 is the number you want to increase by 8%. If you’re feeling a little pessimistic, you also can use this formula to project decreases. Just use a minus sign in front of the percentage figure.

In more complex calculations, you may want to find out what it would cost to give everyone on staff a raise of 4% compared to a raise of 3%. You don’t have to change the percentage in each person’s salary increase formula. Instead, refer each salary increase formula to a cell that you can change once and affect every calculation. For example, the formula =C10*(1+B12) does the calculation based on the percentage listed in cell B12. Copy that formula for each employee and change B12 to different percentages to see the results.