# How to calculate percentage of a number

What is the percentage?

When used with a percentage number, it is used to express the total value of the unit of that number from the units obtained by dividing a whole into one hundred equal parts. For example, the percentage A of a number is calculated by dividing that number by hundred units and finding the total value of A of these units. To give an example over the number 200, when we divide this number by one hundred equal units, the value of one unit will be 200/100 = 2. If we want to calculate 8 percent of the number 200, we need to find the total value of 8 units of 2, which can be calculated as 2 x 8 = 16. If we give a general percentage calculation formula, we can calculate the percentage B of the number A as follows:

Percent B of A = (A / 100) x B

## Can you give examples of how we should make percentage calculations for common situations in daily life?

Of course we will. For 5 different situations that we may encounter frequently in daily life, it is explained below how to calculate the percentage, each corresponding to different transaction types in our application on this page:

Case 1: I know that I will earn 10 percent interest income at the end of the year for the \$2000  money I deposited in the bank. How do I calculate the amount of interest income I will receive?

Mathematical calculation formula: (2000/100) x 10 = \$200

Calculation :

Transaction Type: What is B percent of A number?

Number A: 2000

Number B (%): 10

Case 2: I bought the shoes with a tag price of \$120  from the store for \$90  with a \$30  discount. How can I calculate what percentage discount the store gives me?

Mathematical calculation formula: (30/120) x 100 = 25%

Calculation :

Transaction Type: What percentage of the A number is the B number?

Number A: 30

Number B: 120

## more examples

### 1. Case: What is B% of A Number? Or how is the percentage of a number calculated?

• Our formula = (A / 100) x B
• The number A is divided by 100 and the result is multiplied by the number B.

Sample Calculation: What is 30% of the number 300?

• A = 300, B = 30
• (300/100) x 30 = 90

Example 2: How much interest will the \$50000  I deposit in the bank earn at the end of a year with 10% annual interest?

• A = 50000, B = 10
• (50000/100) x 10 =  \$5000

2. Case: What percentage of a number is b?

• Our formula = (A / B) x 100
• The number A is divided by the number B and the result is divided by a hundred.

Sample Calculation: What percentage of the number 300 is 1000?

• A = 300, B = 1000
• (300/1000) x 100 = 30

3. Case: What is the rate of change from number a to number b?

• Our formula = ((B – A) / A) x 100
• First the number A is subtracted from the number B, the result is divided by the number A. The final value is multiplied by a hundred. If the result is negative, the number has decreased in%, if it is positive, the number has increased in%.

Example Calculation: How many percent increased when the number 300 was 450. Let’s find;

• 450-300 = 150
• 150/300 = 0.5
• 0.5 x 100 = 50. So 50% increased

Example 2: I sold the stock I bought from the stock exchange for 2000 TL for 1500 TL. What percentage of loss have I done on this feeling?

• 1500-2000 = -500
• – 500/2000 = -0.25
• – 0.25 x 100 = – 25. So 25% damage has been done.

4. Case: If we increase the number of A% b, what will be the result?

• Our formula = ((A / 100) x B) + A
• In this calculation type, the number of A is divided by 100, the obtained value is multiplied by B and the number A is added to the result.

Example Calculation: If we increase the number 300 by 20%, what will be the result?

• 300/100 = 3
• 3 x 20 = 60
• 60 + 300 = 360
• 150/300 = 0.5 and 0.5 x 100 = 50.

5. Case: If we decrease the number of A% b, what will be the result?

• Our formula = A – (A / 100) x B)
• In this type of calculation, the number A is divided by 100, the obtained value is multiplied by B and the result is subtracted from the number A.

Example Calculation: If we reduce the number of 300 by 20%, what will be the result?

• 300/100 = 3
• 3 x 20 = 60
• 300 – 60 = 240.

Finding the percentage of a number by means of proportion;

What is 20% of 200? We can explain this calculation formula as follows.

If 100% 200
What is 20%?

when we do inside out; We get 20 x 200 = 4000, 4000/100 = 40.

Finding what percentage of a number is the other number;

What percentage of the number 35 is 350?

If 100% is 350
% x 35;
100 x 35 = 3500 3500/350 = 10 that is 10%.

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