Percentage Notes for SSC Exams

Percentage is the base of almost every arithmetic chapter in SSC Quantitative Aptitude. Profit and loss, discount, interest, data interpretation and even ratio questions use percentages. If your percentage concept is strong, a large part of the maths paper becomes easy. These percentage notes for SSC explain every formula in simple language, with a fraction table, solved examples, practice questions and FAQs.

What Is Percentage?

The word percent means "per hundred". A percentage tells us how many parts out of 100 a quantity has. For example, 25% means 25 out of 100, which is the same as 25/100 or 1/4.

• Percentage = (Part / Whole) x 100.
• x% of y = (x / 100) x y.
• To convert a fraction into a percentage, multiply it by 100.
• To convert a percentage into a fraction, divide it by 100 and reduce.
• Two to five questions of percentage, directly or indirectly, come in every SSC CGL and CHSL Tier 1 paper.

Important Percentage Formulas

Fraction and Percentage Conversion Table

Learning this table is the single best shortcut in this chapter. Most SSC percentage questions can be solved in seconds if you remember these values.

Percentage Change and Successive Change

When a quantity changes, the percentage change is always calculated on the original value. If a value changes twice in a row, the second change is calculated on the new value, so you cannot simply add the two percentages. Use the formula x + y + xy/100. Put a plus sign for an increase and a minus sign for a decrease.

• Two successive increases of 10% each = 10 + 10 + 1 = 21% increase.
• An increase of 20% followed by a decrease of 20% = 20 - 20 - 4 = 4% decrease.
• A decrease of 25% followed by an increase of 20% = -25 + 20 - 5 = 10% decrease.

Price and Consumption Relation

Expenditure = Price x Consumption. If the expenditure has to stay the same, then when the price goes up, the consumption must go down, and the other way round. Use the formulas r/(100 + r) x 100 for a price rise and r/(100 - r) x 100 for a price fall. For a 25% price rise the consumption must fall by 25/125 x 100 = 20%.

Solved Examples

Example 1: Find 20% of 450.
Solution: 20% of 450 = (20 / 100) x 450 = 90.

Example 2: The price of an article rises by 25%. By what percentage must a family reduce its consumption so that the expenditure remains the same?
Solution: Reduction = 25 / (100 + 25) x 100 = 25 / 125 x 100 = 20%.

Example 3: A number is first increased by 20% and then by 10%. What is the net percentage increase?
Solution: Net change = 20 + 10 + (20 x 10) / 100 = 20 + 10 + 2 = 32%.

Example 4: After an increase of 20%, a number becomes 360. Find the original number.
Solution: Original x 120 / 100 = 360, so original = 360 x 100 / 120 = 300.

Example 5: A student scores 40% marks and fails by 30 marks. Another student scores 50% and passes by 20 marks. Find the total marks.
Solution: The difference between 50% and 40% is 10%, and the difference in marks is 30 + 20 = 50. So 10% of total = 50, and the total = 500.

Example 6: The salary of A is 25% more than that of B. By what percentage is the salary of B less than that of A?
Solution: Required % = 25 / (100 + 25) x 100 = 20%.

Quick Tips to Solve Faster

• Learn the fraction table first and convert percentages into fractions to calculate faster.
• To find 10% of a number, just shift the decimal point one place to the left.
• To find x% of y, you can also find y% of x. For example, 8% of 50 = 50% of 8 = 4.
• For successive changes, always use x + y + xy/100 instead of calculating step by step.
• In "more than" and "less than" questions, always take the number after "than" as the base of 100.

Common Mistakes to Avoid

• Adding successive percentages directly without the xy/100 term.
• Taking the new value as the base instead of the original value.
• Mixing the formulas for "A more than B" and "B less than A".
• Writing a decrease with a plus sign in the successive change formula.
• Forgetting to convert the final answer back into a percentage.

Quick Revision Points

• Percentage = (Part / Whole) x 100.
• Successive change = x + y + xy/100.
• Price rises by r%: consumption falls by r/(100 + r) x 100.
• 1/8 = 12.5%, 1/6 = 16.67%, 1/7 = 14.28%, 1/9 = 11.11%.
• Population after n years = P x (1 + r/100)^n.

Practice Questions With Answers

1. What is 15% of 240?
   Answer: 36 (0.15 x 240).
2. 40 is what percent of 250?
   Answer: 16% (40 / 250 x 100).
3. The price of sugar rises from Rs 40 to Rs 50 per kg. What is the percentage increase?
   Answer: 25% (10 / 40 x 100).
4. If A's income is 20% less than B's, then B's income is what percent more than A's?
   Answer: 25% (20 / 80 x 100).
5. The population of a town is 20,000 and grows at 10% every year. What will it be after 2 years?
   Answer: 24,200 (20000 x 1.1 x 1.1).
6. Two successive increases of 10% each are equal to a single increase of how much?
   Answer: 21% (10 + 10 + 1).
7. A number is decreased by 25% and then increased by 20%. What is the net change?
   Answer: 10% decrease (-25 + 20 - 5).
8. In an exam, 80% students passed in English, 70% in Maths and 60% in both. What percent failed in both?
   Answer: 10% (80 + 70 - 60 = 90 passed in at least one).
9. If 35% of a number is 70, what is the number?
   Answer: 200 (70 x 100 / 35).
10. Raj scored 270 marks out of 600. What is his percentage?
    Answer: 45% (270 / 600 x 100).

How to Practise This Chapter

1. Learn the formulas in the table until you can write them without looking.
2. Solve the solved examples again on your own, without reading the solution.
3. Attempt the practice questions above with a timer of 10 minutes.
4. Solve the matching SSC percentage practice paper to test yourself in exam style.
5. Check the previous year papers to see how SSC frames this topic.

Related Notes and Practice Papers

• Profit and Loss Notes
• Ratio and Proportion Notes
• Average Notes
• Simple Interest Notes
• SSC Percentage Practice Paper

Explore More SSC Subjects

SSC exams test many subjects, so connect this topic with the related subjects below:

• Reasoning Notes
• Statistics Notes
• Indian Economy Notes
• English Notes
• General Awareness Notes
• All SSC subjects and notes

Frequently Asked Questions

What is percentage in simple words?

Percentage is a way of writing a number as a part of 100. For example, 40% means 40 out of 100 or 40/100.

How many questions come from percentage in SSC exams?

Two to five questions come directly from percentage in SSC CGL and CHSL Tier 1. Many more questions in profit and loss, interest and data interpretation also use the same concept.

What is the formula for percentage?

Percentage = (Part / Whole) x 100.

How do I find the percentage change?

Percentage change = (New value - Old value) / Old value x 100. A positive result is an increase and a negative result is a decrease.

What is the successive percentage change formula?

For two successive changes of x% and y%, the net change is x + y + xy/100. Use a negative sign for a decrease.

How do I calculate percentage quickly?

Learn the fraction-percentage table, find 10% by shifting the decimal and build other values from it, for example 15% = 10% + 5%.

What is the relation between price and consumption?

Expenditure is price multiplied by consumption. To keep the expenditure constant, a price rise of r% needs a consumption fall of r/(100 + r) x 100 %.

Is percentage important for other chapters?

Yes. Profit and loss, discount, simple and compound interest, ratio and data interpretation all use percentage calculations.

How should I practise percentage for SSC?

Learn the table and formulas, solve the examples in these notes, and then attempt a timed practice paper and previous year questions.

Which book or notes are best for percentage?

These notes along with a full practice paper and previous year papers are enough for SSC-level percentage questions.