SSC CGL 2027 Percentage Questions Based on Successive Changes

Percentage is one of the most important topics in Quantitative Aptitude for SSC CGL preparation. Questions based on successive percentage changes frequently test a candidate's understanding of increases, decreases, discounts, population changes, salary revisions and price variations. Instead of calculating every change separately, candidates can use simple formulas and shortcuts to solve these questions accurately.

In this guide, you will learn the meaning of successive percentage changes, important formulas, solved examples, common mistakes and practice questions for SSC CGL 2027. Use this topic-wise approach to improve calculation speed and build confidence for competitive examinations.

1. What Are Successive Percentage Changes?

Successive percentage changes occur when a value changes by a certain percentage and then changes again by another percentage. The second percentage is generally calculated on the updated value, not the original value.

For example, if a product's price increases by 20% and then decreases by 10%, the second change is applied to the increased price. Therefore, the final result is not obtained simply by subtracting 10 from 20.

These questions can be solved quickly by using multipliers or the standard successive change formula.

2. Important Successive Percentage Formula

When a value changes successively by x% and y%, the net percentage change is:

Example: A value increases by 20% and then decreases by 10%.

Here, x = 20 and y = -10.

Net change = 20 + (-10) + (20 × -10)/100

Net change = 20 - 10 - 2 = -2%

Therefore, the final value decreases by 2% compared with the original value.

Multiplier Method

The multiplier method is another useful technique. For an increase of x%, multiply the original value by (100 + x)/100. For a decrease of x%, multiply it by (100 - x)/100.

• 20% increase: multiply by 1.20.
• 10% decrease: multiply by 0.90.
• 15% increase: multiply by 1.15.
• 25% decrease: multiply by 0.75.

For a 20% increase followed by a 10% decrease, the combined multiplier is 1.20 × 0.90 = 1.08. The final value is 108% of the original, so the net change is an 8% increase.

3. Solved Examples for SSC CGL 2027

Example 1: Two Successive Increases

Question: The price of an item increases by 10% and then by 20%. Find the total percentage increase.

Solution:

Net change = 10 + 20 + (10 × 20)/100

= 30 + 2 = 32%

Answer: 32% increase.

Example 2: Two Successive Decreases

Question: A product's price decreases by 20% and then by 10%. Find the overall percentage decrease.

Solution:

Net change = -20 - 10 + [(-20 × -10)/100]

= -30 + 2 = -28%

Answer: 28% decrease.

Example 3: Increase Followed by Decrease

Question: A number increases by 25% and then decreases by 20%. What is the net change?

Solution:

Net change = 25 - 20 + (25 × -20)/100

= 5 - 5 = 0%

Answer: No net change.

Example 4: Salary Revision

Question: An employee earns ₹30,000 per month. The salary increases by 10% and then by another 5%. Find the final salary.

Solution:

After the first increase = ₹30,000 × 1.10 = ₹33,000.

After the second increase = ₹33,000 × 1.05 = ₹34,650.

Answer: ₹34,650. The total increase is ₹4,650, which is 15.5% of the original salary.

Example 5: Population Change

Question: A town has a population of 50,000. Its population increases by 8% in one year and by 5% in the next year. Find the population after two years.

Solution:

After the first year = 50,000 × 1.08 = 54,000.

After the second year = 54,000 × 1.05 = 56,700.

Answer: 56,700 people. The total increase is 13.4%, not 13%.

4. Successive Discounts

Successive discounts are commonly used in percentage-based arithmetic questions. When two discounts are applied one after another, the second discount is calculated on the reduced price.

Formula:

Here, a and b are the two discount percentages.

Example: A shop offers discounts of 20% and 10% on an item marked at ₹2,000.

Equivalent discount = 20 + 10 - (20 × 10)/100 = 28%.

Total discount = ₹2,000 × 28/100 = ₹560.

Final selling price = ₹2,000 - ₹560 = ₹1,440.

Answer: ₹1,440.

5. Important Shortcuts and Tips

• Same increase and decrease: If a value increases by x% and then decreases by x%, the net result is a decrease of x²/100%.
• Same successive increases: For two increases of x%, use 2x + x²/100.
• Use a base value: When the question does not give an actual value, assume 100 to simplify calculations.
• Use multipliers: Multipliers are especially useful when three or more changes are involved.
• Check the base: Each new percentage change is usually applied to the updated value.
• Read the question carefully: Identify whether it asks for the final value, the net change or the percentage difference.

6. Common Mistakes to Avoid

1. Adding percentages directly: A 20% increase followed by a 10% decrease is not a 10% net increase.
2. Using the original value for every change: The second change generally applies to the updated amount.
3. Ignoring negative signs: Treat decreases as negative percentages when using the net change formula.
4. Confusing discount and price change: Successive discounts reduce the marked price one after another.
5. Rushing calculations: Write the formula first and verify the final sign before choosing an answer.

7. Practice Questions for SSC CGL 2027

Attempt these questions without checking the answers first. Use the formula or multiplier method to improve accuracy.

Answer Key with Quick Explanations

1. B) 26.5% — 15 + 10 + (15 × 10)/100 = 26.5%.

2. A) 44% — 30 + 20 - (30 × 20)/100 = 44% decrease.

3. A) 5% increase — 40 - 25 + (40 × -25)/100 = 15 - 10 = 5% increase.

4. B) ₹1,080 — ₹1,500 × 0.90 × 0.80 = ₹1,080.

5. B) ₹47,040 — ₹40,000 × 1.12 × 1.05 = ₹47,040.

8. How to Prepare Successive Percentage Questions

Begin by revising basic percentage conversions, such as fractions into percentages and percentage increase or decrease. Then practise the successive change formula using small values before moving to word problems involving salaries, prices, population and discounts.

Maintain a notebook of formulas and note the mistakes you make during practice. Solve timed question sets regularly, but prioritise accuracy before increasing speed. After completing a mock test, review every incorrect answer and identify whether the error occurred in the formula, calculation or interpretation of the question.

For SSC CGL 2027, candidates should also check the official notification and syllabus when released to confirm the applicable examination pattern. This article is a topic-wise preparation resource and does not guarantee that a particular question will appear in the examination.

Frequently Asked Questions

1. What is the formula for successive percentage changes?

The formula is x + y + (xy/100), using positive signs for increases and negative signs for decreases.

2. What happens when a value increases and decreases by the same percentage?

The final value is lower than the original. For equal changes of x%, the net decrease is x²/100%.

3. Are successive discounts calculated on the original price?

No. The second discount is calculated on the price remaining after the first discount.

4. How can I solve these questions faster?

Learn the formula, practise multiplier calculations and use 100 as a base value when it simplifies the problem.

5. Is successive percentage change useful for SSC CGL Quantitative Aptitude?

Yes. It is a useful arithmetic concept for practising questions involving percentage changes, discounts, prices, salaries and population.