Multiply by a percentage
Maybe it’s been a while since you’ve worked with percentages in Excel. Or if you’re like me, percentages might not be your favorite kind of math. It’s all easier if you let Excel do the work for you.
And if you need to do something such as find the percentage of a total, we can help you with that in the article Calculate percentages.
Multiply an entire column of numbers by a percentage
In this example table, we’ve got just a few numbers to multiply by 15 percent. Even if the column has 100 or 1000 cells of data, Excel can still handle it in a few steps. Here’s how:

Enter the numbers you want to multiply by 15% in an empty column.

In an empty cell enter the percentage, which would be 15%, and then copy that number by pressing Ctrl + C.

Select the range of cells in cells in A1:A5 by dragging down the column.

Right click the selected cells, and then click Paste Special (do not click the arrow next to Paste Special).

Click Values > Multiply. Click OK.
And here’s the result: all the numbers multiplied by 15%.
Reduce or increase an amount by a percentage
Perhaps you want to decrease or increase your weekly food expenditures by 25%. To find the amount, use a formula to get a total with a percentage reduced or added.
In our food example, if B2 is the amount that you spend, and C2 is the percentage you want to reduce that amount by, here’s the formula you’d enter in cell D2:

=B2*(1C2)
In the formula, 1 is used to represent 100%. The numbers inside the parentheses are calculated first, so C2 is subtracted from 1, to give us 75%, and the result is multiplied by B2 to get a result of 56.25 for Week 1.
To copy the formula in cell D2 down the column, doubleclick the small square green box in the lowerright corner of cell D2. You get the results without retyping the formula.
If you wanted to increase the amount by 25%, you’d enter the same formula in cell D2, but change the negative sign to a plus sign. Here’s the formula:

=B2*(1+C2)