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CBSE Class 8 Maths Chapter 8 - Comparing Quantities Formulas

Last updated date: 23rd May 2024
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Comparing Quantities Formulas for CBSE Class 8 Maths - Free PDF Download

Formulas of Comparing Quantities in Class 8 is quite essential to not only understand the theory of different mathematical quantities but also to solve numerical problems related to it. These Comparing Quantities Class 8 formulas are typically useful in finding out the rate of interest, tax value, cost price, selling price and profit and loss on a good or services etc. Thus, understanding the formula of Comparing Quantities in Class 8 is not only helpful academically but in future for daily application as well. Vedantu is a platform that provides free (CBSE) NCERT Solution and other study materials. Subjects like Science, Maths, English will become easy to study if you have access to NCERT Solution for Class 8 Science, Class 8 Maths Solutions and solutions of other subjects.

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Maths Formulas For Class 8 Comparing Quantities

Discount Formulas

Discount is the reduction in the value induced on the Marked Price (MP).

Discount = Marked Price – Sale Price

Discount = Discount % of the Marked Price

The additional expenses that we make after buying a product are called the Overhead expenses. These are included in the Cost Price (CP) of that specific product.

Cost Price = Purchase Price + Overhead Expenses

GST (Goods and Service Tax) is computed typically on the supply of the goods.

Tax = Tax % of the Bill Amount.

Compound Interest Formulas

Compound Interest (CI) is the amount of interest that is compounded on the basis of the previous year’s amount.

Formula For Compound Interest Compounded Annually: A=P (1+R100) t

In which,

P = Principal,

r = Rate of Interest, and

t = Time Period

Formula For Compound Interest Compounded Half Yearly: A=P (1+R200)2t

R/2 = Half-yearly Rate,

2t = Number of Half-Years

Unitary Method For Comparing Quantities

The unitary method is one of the most effective techniques to solve problems on ratio, proportion and percentage (s). Under this method, we first find the value of one unit and then find the value of the number of units needed. Thus, the short unitary method consists of the following two steps:

Step 1 = Identify the value of one unit.

Step 2 = Evaluate the value of the number of units needed.


Percentages are methods to compare quantities. They are numerators of fractions with denominator 100 or it generally implies per 100 values. The percent is basically extracted from the Latin term ‘per centum’ stating ‘per hundred’. It is represented by the symbol %. For example 1% means 1/100= .01. We can use either unitary method or we need to convert the fraction to an equivalent fraction with denominator 100.

Important Formulas of Comparing Quantities Class 8 NCERT

Cost Price = Selling Price – Profit

Cost Price = Selling Price + Loss

Selling Price = Cost Price + Profit

Selling Price = Cost Price – Loss

Profit (P) = Selling Price - Cost Price

Loss = Cost Price - Selling Price

Profit % = 100

Loss % = 100

Discount (D) = Marked Price (M.P.) – Selling price (S.P)

Discount % = 100

Net Price = Selling Price = Marked Price – Discount

Important Sales Tax Formulas:-

Bill Amount = Cost of commodity + Sales tax

Value added tax (VAT) = Tax charged – Tax paid.

Value added tax = Tax % (Selling Price – Cost Price)

Solved Examples

Example 1:

A sum of Rs. 20,000 is borrowed by Mr Mehra at an interest rate of 10% per annum for 2 years. Calculate the simple interest on this sum and the amount to be paid by Mr Mehra at the end of 2 years.


On Rs. 100, interest charged for 1 year is 10%.

So, on Rs. 10,000, interest charged = 2000

= 2500 Interest for 2 years

= 2000 × 2

= 4000

Amount to be paid by Mr Mehra at the end of 2 years

= Principal Amount + Interest

= 20000 + 4000

= 24000


A woman purchases a handbag for Rs. 5000 and later sells it at a loss of 20%. What is the selling price of the handbag?


C.P of the handbag = Rs.5000

Loss percentage = 20%

As we are already aware, Loss percentage = (Loss/Cost Price) x 100

20 = (loss/5000) x 100

Therefore, Loss = 1000 rs.

As we know,

Loss = CP – SP

therefore, SP = CP – Loss

= 5000 – 1000

Selling Price = R.4000/-

FAQs on CBSE Class 8 Maths Chapter 8 - Comparing Quantities Formulas

Q1. Which Book is Most Preferred for Learning Class 8 Maths Formulas?

Answer: NCERT books are considered to be most important for practising CBSE maths and also if you want to know all the important Class 8 Maths formulas, including all formulas of Comparing Quantities Class 8.

Q2. Is There any Website that Offers Free Class 8 Practice Questions Online?

Answer: Vedantu e-learning provides students with free Class 8 practice questions to learn and score excellently in your examinations.

Q3. How to Make the Best Use of Class 8 Maths Formulas?

Answer: The list of Class 8 Maths formulas will significantly help you during the time you get stuck in questions while practising the subject or even when writing the final paper. The formulas and attributes will be very much helpful for you to go through a quick revision. This way students are not only able to prepare well but score better.

Q4. How will Class 8 Maths Formulas Help me get Through Class 8?

Answer: These formulas for Comparing Quantities Class 8 are taken from the elementary Class 8 NCERT book. Hence, it’ll prove quite useful for you no matter what board of education you are studying in. These formulas are present on the dedicated page of Vedantu which is made available unit wise and class wise so that you don’t have to go back and forth. Hence, Class 8 Maths Comparing Quantities all formulas will come in handy at the time of revision.