Sometimes percentages can be frustrating because it’s not always easy to remember what we learned about them in school. Let Excel do the work for you – simple formulas can help you find the percentage of a total, for example, or the percentage difference between two numbers.
Find the percentage of a total
Let's say that you answered 42 questions out of 50 correctly on a test. What is the percentage of correct answers?

Click any blank cell.

Type =42/50, and then press RETURN .
The result is 0.84.

Select the cell that contains the result from step 2.

On the Home tab, click .
The result is 84.00%, which is the percentage of correct answers on the test.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .
Find the percentage of change between two numbers
Let's say that your earnings are $2,342 in November and $2,500 in December. What is the percentage of change in your earnings between these two months? Then, if your earnings are $2,425 in January, what is the percentage of change in your earnings between December and January? You can calculate the difference by subtracting your new earnings from your original earnings, and then dividing the result by your original earnings.
Calculate a percentage of increase

Click any blank cell.

Type =(25002342)/2342, and then press RETURN .
The result is 0.06746.

Select the cell that contains the result from step 2.

On the Home tab, click .
The result is 6.75%, which is the percentage of increase in earnings.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .
Calculate a percentage of decrease

Click any blank cell.

Type =(24252500)/2500, and then press RETURN .
The result is 0.03000.

Select the cell that contains the result from step 2.

On the Home tab, click .
The result is 3.00%, which is the percentage of decrease in earnings.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .
Find the total when you know the amount and percentage
Let's say that the sale price of a shirt is $15, which is 25% off the original price. What is the original price? In this example, you want to find 75% of which number equals 15.

Click any blank cell.

Type =15/0.75, and then press RETURN .
The result is 20.

Select the cell that contains the result from step 2.

In newer versions:
On the Home tab, click .
The result is $20.00, which is the original price of the shirt.
In Excel for Mac 2011:
On the Home tab, under Number, click Currency
The result is $20.00, which is the original price of the shirt.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .
Find an amount when you know the total and percentage
Let's say that want to purchase a computer for $800 and must pay an additional 8.9% in sales tax. How much do you have to pay for the sales tax? In this example, you want to find 8.9% of 800.

Click any blank cell.

Type =800*0.089, and then press RETURN.
The result is 71.2.

Select the cell that contains the result from step 2.

In newer versions:
On the Home tab, click .
In Excel for Mac 2011:
On the Home tab, under Number, click Currency
The result is $71.20, which is the sales tax amount for the computer.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .
Increase or decrease a number by a percentage
Let's say that you spend an average of $113 on food each week, and you want to increase your weekly food expenditures by 25%. How much can you spend? Or, if you want to decrease your weekly food allowance of $113 by 25%, what is your new weekly allowance?
Increase a number by a percentage

Click any blank cell.

Type =113*(1+0.25), and then press RETURN .
The result is 141.25.

Select the cell that contains the result from step 2.

In newer versions:
On the Home tab, click .
In Excel for Mac 2011:
On the Home tab, under Number, click Currency
The result is $141.25, which is a 25% increase in weekly food expenditures.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .
Decrease a number by a percentage

Click any blank cell.

Type =113*(10.25), and then press RETURN .
The result is 84.75.

Select the cell that contains the result from step 2.

In newer versions:
On the Home tab, click .
In Excel for Mac 2011:
On the Home tab, under Number, click Currency
The result is $84.75, which is a 25% reduction in weekly food expenditures.
Note: To change the number of decimal places that appear in the result, click Increase Decimal or Decrease Decimal .