There are many uses of percentage in day to day life, like:

- You can calculate the discount on your clothes.
- You can check the quantity by using a percentage.
- It helps to estimate part of an area.
- You can find an interest in the bank, the amount of money spent or borrowed.
- You can find the result of your exam.

For example, out of 50 students in your class, 80% of them are going to the picnic. How will you find the exact number of the students going?

Total number of students = 50

Percentage of students going to picnic = 80%

Number of students going to picnic = a

Percentage = given quantity x 100 / total quantity

80 = a x 100 / 50

80 x 50 = 100a

4000 = 100a

4000/100 = a

a = 40

This means out of 50 students in the class, 40 of them are going to the picnic.

While **converting decimal to a percentage**, first convert decimal into a fraction, 0.2 becomes 2/10. Then multiply it by 100.

What if the question is reversed and you have been asked to convert a percentage to decimal or fraction?

For example: Convert 10% into fraction and decimal.

10% = 10/100, so

Fraction = 1/10

Decimal = 0.1

You can use percentage for calculating **prices related to an item or buying and selling. **Whenever shopkeepers buy a product, they sell it at a higher price. The buying price of an item is called **Cost Price (CP)**. The selling price of an item is called **Selling Price (SP)**. To check whether the shopkeeper earned the benefit or not, it is found by using profit or loss. Prices related to an item or buying and selling is in terms of Cost Price or Selling Price.

CP < SP, this is profit = SP-CP

CP = SP, neither profit nor loss

CP > SP, this is loss = CP-SP

If CP < SP, then you made a profit = SP – CP.

For example: A toy bought for INR 72 is sold at INR 80. Here, the shopkeeper is getting a profit of INR 8 (SP-CP = 80-72).

For example: A T-shirt bought for INR 120 is sold at INR 100. Here, the shopkeeper is having a loss of INR 20 (CP-SP = 120-100).

In the examples mentioned above, if you want to find the **profit or loss as a percentage** for the shopkeeper, here is the way:

For the toy, profit was INR 8, so

Profit % = Profit x 100 / CP = 8 x 100 / 72 = 11.11%

For the T-shirt, the loss was INR 20, so

Loss % = Loss x 100 / CP = 20 x 100 / 120 = 16.66%

We use percentage for calculating **interest for multiple years**. The money that has been borrowed is called the Principal. For keeping the money for some time, the borrower has to pay some extra money to the bank, which is called interest. To find the total sum of money to be paid at the end of the year, the amount of money borrowed and you must add interest. This is called Amount.

Amount = Principal + Interest

For example, if the bank says 10% per annum interest, this means for every INR 100 borrowed, you must pay INR 10 as interest per year.