SSC GD Percentage Notes 2026 – Complete Handwritten Notes, Formulas & Solved Questions

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SSC GD Percentage

Complete Handwritten Notes • Very Simple English • SSC GD 2026

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SSC GD Percentage Notes – Complete Chapter

Easy idea: Percentage means “per hundred”. The symbol % means that a number is taken out of 100. Percentage is used in marks, profit and loss, discount, salary, population, increase and decrease. Learn the basic conversion first and most questions become easier.

1. Meaning of Percentage

Percentage tells how many parts are there out of 100.

\[x\%=\frac{x}{100}\]\[1\%=\frac1{100}\]

Example: 25% means 25 parts out of 100.
\(25\%=\frac{25}{100}=\frac14\).

2. Conversion of Percentage, Fraction and Decimal

Percentage	Fraction	Decimal
5%	1/20	0.05
10%	1/10	0.10
12.5%	1/8	0.125
20%	1/5	0.20
25%	1/4	0.25
33⅓%	1/3	0.333...
50%	1/2	0.50
75%	3/4	0.75
100%	1	1.00
125%	5/4	1.25
150%	3/2	1.50

Shortcut: To change a percentage into a decimal, divide by 100. To change a decimal into percentage, multiply by 100.

3. Finding Percentage of a Number

\[x\%\text{ of }N=\frac{x}{100}\times N\]

Example: Find 25% of 240.
\(25\%\text{ of }240=\frac{25}{100}\times240\)
\(=\frac14\times240=60\).
Answer = 60

Example: Find 15% of 320.
10% = 32, 5% = 16.
32 + 16 = 48.
Answer = 48

4. Finding What Percent One Number Is of Another

\[\text{Percentage}=\frac{\text{Part}}{\text{Whole}}\times100\]

Example: 45 is what percent of 180?
\(\frac{45}{180}\times100=25\%\).
Answer = 25%

5. Finding the Whole Number

Sometimes the percentage and part are given, and we need to find the total.

\[\text{Whole}=\frac{\text{Part}\times100}{\text{Percentage}}\]

Example: 30% of a number is 72. Find the number.
\(N=\frac{72\times100}{30}=240\).
Answer = 240

6. Percentage Increase

When a value becomes larger, the change is an increase.

\[\text{Increase\%}=\frac{\text{Increase}}{\text{Original}}\times100\]

Example: Price changes from 400 to 460.
Increase = 460 − 400 = 60.
Increase% = \(\frac{60}{400}\times100=15\%\).
Answer = 15%

7. Percentage Decrease

\[\text{Decrease\%}=\frac{\text{Decrease}}{\text{Original}}\times100\]

Example: A number falls from 800 to 680.
Decrease = 120.
Decrease% = \(\frac{120}{800}\times100=15\%\).
Answer = 15%

Important: In increase/decrease questions, always divide by the original value, not the new value.

8. New Value After Increase or Decrease

\[\text{New Value}=\text{Original}\left(1+\frac r{100}\right)\]\[\text{New Value}=\text{Original}\left(1-\frac r{100}\right)\]

Example: Salary = ₹20,000. Increase = 10%.
Increase = ₹2,000.
New salary = ₹22,000.

Example: Price = ₹800. Decrease = 15%.
Decrease = ₹120.
New price = ₹680.

9. Successive Percentage Change

When a value changes more than once, do not simply add the percentages in every case.

\[\text{Net Change\%}=a+b+\frac{ab}{100}\]\[\text{Net Decrease\%}=a+b-\frac{ab}{100}\]

The first formula is used for two successive increases of \(a\%\) and \(b\%\). The second is used for two successive decreases of \(a\%\) and \(b\%\).

Example: A value increases by 10% and then by 20%.
Net increase = \(10+20+\frac{10\times20}{100}=32\%\).
Answer = 32%

Example: A value decreases by 10% and then by 20%.
Net decrease = \(10+20-\frac{10\times20}{100}=28\%\).
Answer = 28%

10. Increase Followed by Decrease

\[\text{Net Change\%}=a-b-\frac{ab}{100}\]

Example: A number increases by 20% and then decreases by 10%.
Net change = \(20-10-2=8\%\).
Net increase = 8%

11. Reverse Percentage

When the final value is known and we need the original value, divide by the correct multiplier.

\[\text{Original}=\frac{\text{Final}}{1+\frac r{100}}\]\[\text{Original}=\frac{\text{Final}}{1-\frac r{100}}\]

Example: After a 20% increase, price is ₹720. Find original price.
Original = \(720\div1.20=600\).
Answer = ₹600

12. Percentage in Marks

\[\text{Percentage}=\frac{\text{Marks Obtained}}{\text{Total Marks}}\times100\]

Example: A student gets 420 marks out of 600.
\(\frac{420}{600}\times100=70\%\).
Answer = 70%

13. Population and Other Changes

The same percentage increase/decrease rules are used for population, production, salary, price and quantity.

Example: Population = 50,000. Increase = 8%.
Increase = 4,000.
New population = 54,000.

14. Percentage and Ratio

\[A:B=x:y\Rightarrow A=\frac{x}{x+y}\times100\%\text{ of total}\]

Example: Ratio of boys:girls = 3:2.
Boys as percentage of total = \(\frac35\times100=60\%\).
Girls = 40%.

15. Percentage Points vs Percentage Change

A change from 40% to 50% is an increase of 10 percentage points. The percentage increase relative to 40% is \(\frac{10}{40}\times100=25\%\). These two ideas are different.

16. Fraction Tricks for SSC GD

• 10% = 1/10
• 5% = 1/20
• 20% = 1/5
• 25% = 1/4
• 50% = 1/2
• 75% = 3/4
• 12.5% = 1/8
• 33⅓% = 1/3
• 66⅔% = 2/3
• 125% = 5/4

17. SSC GD Solved Questions

Q1. Find 35% of 240.

30% = 72 and 5% = 12.
72 + 12 = 84.
Answer = 84

Q2. 48 is what percent of 160?

\(\frac{48}{160}\times100=30\%\).
Answer = 30%

Q3. 40% of a number is 96. Find the number.

\(N=96\times100/40=240\).
Answer = 240

Q4. A number increases from 500 to 575. Find increase%.

Increase = 75.
\(75/500\times100=15\%\).
Answer = 15%

Q5. A price of ₹900 is reduced by 20%. Find new price.

Decrease = ₹180.
New price = ₹720.
Answer = ₹720

Q6. A salary of ₹10,000 increases by 15%. Find new salary.

Increase = ₹1,500.
New salary = ₹11,500.
Answer = ₹11,500

Q7. A value increases by 10% and then 20%. Find net increase.

\(10+20+2=32\%\).
Answer = 32%

Q8. A value decreases by 20% and then 10%. Find net decrease.

\(20+10-2=28\%\).
Answer = 28%

Q9. After a 25% increase, a number becomes 500. Find original.

Original = \(500/1.25=400\).
Answer = 400

Q10. 420 out of 700 is what percentage?

\(420/700\times100=60\%\).
Answer = 60%

Q11. In a class, boys:girls = 2:3. Boys are what percentage?

Total parts = 5.
\(2/5\times100=40\%\).
Answer = 40%

Q12. A population of 25,000 increases by 12%. Find new population.

Increase = 3,000.
New population = 28,000.
Answer = 28,000

Q13. A number is reduced by 30% and becomes 350. Find original.

Original = \(350/0.70=500\).
Answer = 500

Q14. A student scores 360 out of 450. Find percentage.

\(360/450\times100=80\%\).
Answer = 80%

Q15. A number increases by 20% and then decreases by 20%. Find net change.

Using multiplier: \(1.20\times0.80=0.96\).
Net decrease = 4%.
Answer = 4% decrease

18. Practice Set

1. Find 15% of 360.
2. Find 22% of 250.
3. 60 is what percent of 240?
4. 45% of a number is 180. Find the number.
5. A value rises from 600 to 690. Find increase%.
6. A value falls from 900 to 765. Find decrease%.
7. Find new value of 800 after 15% increase.
8. Find new value of 1200 after 25% decrease.
9. A value increases by 10% and then 30%. Find net increase.
10. A value decreases by 20% and then 15%. Find net decrease.
11. After a 25% increase, value is 750. Find original.
12. After a 20% decrease, value is 560. Find original.
13. 540 marks out of 720 is what percentage?
14. Ratio boys:girls = 3:2. Find boys percentage.
15. Population 40,000 increases by 5%. Find new population.
16. Salary ₹24,000 decreases by 12.5%. Find new salary.
17. Find 33⅓% of 270.
18. Find 125% of 240.
19. A number increases by 20% and decreases by 10%. Find net change.
20. A number decreases by 30% and then increases by 30%. Find net change.

19. Answer Key

Answers

1. 54   2. 55   3. 25%   4. 400   5. 15%
6. 15%   7. 920   8. 900   9. 43%   10. 32%
11. 600   12. 700   13. 75%   14. 60%   15. 42,000
16. ₹21,000   17. 90   18. 300   19. 8% increase   20. 9% decrease

20. Common Mistakes

• Do not divide by the new value when finding percentage increase or decrease; use the original value.
• Do not add successive percentages blindly.
• Keep percentage, fraction and decimal conversion clear.
• Read whether the question asks for part, whole or percentage.
• In reverse percentage questions, divide by the correct multiplier.

21. Quick Revision

\[x\%=\frac{x}{100}\]\[\text{Part\%}=\frac{\text{Part}}{\text{Whole}}\times100\]\[\text{Increase\%}=\frac{\text{Increase}}{\text{Original}}\times100\]\[\text{Decrease\%}=\frac{\text{Decrease}}{\text{Original}}\times100\]\[\text{Original}=\frac{\text{Final}}{1\pm r/100}\]\[\text{Successive increases: }a+b+ab/100\]

Golden rule: Percentage questions become easy when you clearly identify the part, whole, original value and change.

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