Let’s say you have a value, and you want to add or subtract a percentage of it. For example, if you want to add 10 percent to 100, or you want to deduct 10 percent from it. It’s a quick and easy formula calculation in Excel that you can do.

Below are the formulas that you can use to increase and decrease a particular percentage from a numeric value.

**To Increase:***=original_value*(100%+increase_percentage%)***To Decrease:***=original_value*(100%-decrease_percentage%)*

In this tutorial, we will learn to write this formula:

## Formula to Add or Increase a Value by a Percentage

You can use the below steps:

- First, in a cell, refer to the cell where you have the original value.
- After that, enter the asterisk operator for multiplication.
- Now, enter the opening parentheses and then enter “100%”.
- Next, enter the addition operator and 10%, which is the value you want to increase with.
- In the end, enter the closing parentheses and hit enter to get the result.

`=A1*(100%+10%)`

The moment you hit enter, it will return the value by increasing it to 110%.

You also use the formula in the flowing way where instead of using 100% you can use a 1 and for the increased percentage, you can decimal value.

`=A1*(1+0.1)`

## Formula to Subtract or Decrease a Value by a Percentage

You can use the below steps to write this formula:

- First, enter = in a cell and refer to the cell with the original value.
- After that, enter the closing parentheses and enter 100%.
- Next, use the subtraction sign to deduct and enter the percentage value that you want to decrease.
- In the end, enter the closing parentheses and hit enter to get the result.

`=A1*(100%-10%)`

The moment you hit enter, it will return a new value with a decrease.

And you can also use the formula in the following way where you can use the 1 instead of the 100%, and .1 to specify the 10%.

## How do these Formulas Work?

To understand these formulas, you need to split them into three parts:

- Original Value
- 100% or 1
- Increase and Decrease (In Percentage or Decimal)

If you want to decrease a value by 15 percent, you just need to use 15% with the minus operator, or you can also use -0.15.

A percentage value is a number formatted as a percentage in Excel. When you enter 100% in a cell, Excel treats it as a 1 and formats it with the percentage. That’s why you can use 1 or 100% in the formula. And to specify the increase, you can use a decimal value or a percentage value.