Study Material — 29 PYQs (2018–2023) · Concept Notes · Shortcuts
NDA Basic Percentage is a frequently tested subtopic — 29 previous year questions from 2018–2023 papers are included below with concept notes, key rules and shortcut tricks.
29 questions from actual NDA papers · all shown free · click option to reveal solution
Exam Q 12020Previous Year Pattern
A shopkeeper marks an item at ₹500. He offers a discount of 12% on the marked price. What is the selling price of the item?
Exam Q 22023Previous Year Pattern
In an examination, a student scored 72% and obtained 360 marks. What is the total marks of the examination?
Exam Q 32023Previous Year Pattern
A shirt costs ₹800. Its price is increased by 20%. What is the new price?
Exam Q 42023Previous Year Pattern
If 45% of a number is 360, what is 20% of that number?
Exam Q 52023Previous Year Pattern
What is 25% of 480?
Exam Q 62023Previous Year Pattern
A shopkeeper marks an item at ₹500. He offers a discount of 15% on the marked price. What is the selling price?
Exam Q 72023Previous Year Pattern
A book's price was reduced by 30% and now costs ₹490. What was the original price?
Exam Q 82023Previous Year Pattern
In a class of 200 students, 45% are boys. How many girls are there?
Exam Q 92023Previous Year Pattern
If 15% of a number is 45, what is the number?
Exam Q 102023Previous Year Pattern
The price of a commodity increased by 25%. If the new price is ₹750, what was the original price?
Exam Q 112023Previous Year Pattern
A student scored 72 marks out of 120 in an exam. What is the percentage score?
Exam Q 122023Previous Year Pattern
The price of a commodity increased by 20%, and then decreased by 10%. What is the net percentage change in the price?
Exam Q 132023Previous Year Pattern
A product's price was reduced by 15%, and then the reduced price was increased by 15%. What is the net percentage change from the original price?
Exam Q 142023Previous Year Pattern
The price of petrol increased by 20% and then decreased by 10%. What is the net percentage change?
Exam Q 152023Previous Year Pattern
A shopkeeper marks an item at ₹500. He offers a discount of 12% on the marked price. What is the selling price?
Exam Q 162023Previous Year Pattern
A number is increased by 25%. If the new number is 500, what was the original number?
Exam Q 172018Previous Year Pattern
A student scored marks in three subjects: 75 out of 100 in Maths, 80 out of 100 in English, and 65 out of 100 in Science. What is the overall percentage scored by the student?
Exam Q 182023Previous Year Pattern
In an examination, a student scored 75% marks and obtained 300 marks. What are the total marks for the examination?
Exam Q 192023Previous Year Pattern
A student scored 72% in English and 88% in Mathematics. If English has a weightage of 40% and Mathematics has a weightage of 60%, what is the weighted average percentage?
Exam Q 202020Previous Year Pattern
A shopkeeper marks up the cost price of an item by 40%. He then offers a discount of 10% on the marked price. If the cost price is ₹500, what is his profit percentage?
Exam Q 212023Previous Year Pattern
In an examination, 65% of students passed. If 455 students passed, how many students appeared in total?
Exam Q 222023Previous Year Pattern
A quantity increases by 20%, then decreases by 25%, and finally increases by 10%. What is the net percentage change from the original quantity?
Exam Q 232023Previous Year Pattern
A person's salary is increased by 25% in January and then decreased by 20% in February. If his salary in February is ₹12,000, what was his original salary in December?
Exam Q 242023Previous Year Pattern
A student scored 72% in English, 68% in Mathematics, and 80% in Science. The maximum marks for each subject are 150, 120, and 100 respectively. What is the overall percentage of marks obtained across all three subjects?
Exam Q 252023Previous Year Pattern
In an election, candidate A received 45% of votes, candidate B received 35% of votes, and the remaining votes were invalid. If the total number of valid votes was 8000, how many invalid votes were cast?
Exam Q 262023Previous Year Pattern
A shopkeeper marks up goods by 60% above cost price. He then offers a discount of 25% on the marked price. If the cost price of an item is ₹800, what is his profit percentage?
Exam Q 272023Previous Year Pattern
A container has 120 litres of a mixture containing 40% alcohol. How many litres of pure alcohol must be added to make the alcohol content 60%?
Exam Q 282020Previous Year Pattern
A shopkeeper marks up goods by 60% above cost price. He then offers a discount of 25% on the marked price during a sale. Later, he realizes his profit margin is lower than expected and increases the selling price by 20%. What is his final profit percentage?
Exam Q 292023Previous Year Pattern
The price of a commodity increases by 20% in the first year and decreases by 15% in the second year. If the final price is ₹1224, what was the original price?
Concept Notes
Basic Percentage— Rules & Concept
Core ConceptRead this first — the foundation of the topic
Percentage means 'per hundred'. It is a way to express a number as a part of 100. The word comes from Latin 'per centum' meaning 'out of 100'. Simple idea: If you score 45 out of 50, what is your percentage? You convert that fraction into 'out of 100'. That number is your percentage.
Think of percentage as a universal comparison tool. It lets you compare any two quantities on the same scale of 100. ---
Key RulesCore rules you must know cold
Rule 2
The base changes depending on the question. Always identify WHAT you are taking the percentage OF
Rule 3
Percentage has no unit. It is a pure number
Rule 4
A percentage can be greater than 100
Example
150% of 200 = 300.
---
Formula BlockMemorise — at least one formula appears in every paper
--
Basic Formula:
Percentage = (Part / Whole) x 100
To find Part when Percentage is given:
Part = (Percentage / 100) x Whole
To find Whole when Part and Percentage are given:
Whole = (Part x 100) / Percentage
Fraction to Percentage:
Multiply fraction by 100
Example: 3/4 = (3/4) x 100 = 75%
Percentage to Fraction:
Divide by 100
Example: 40% = 40/100 = 2/5
---
Exam PatternsWhat examiners ask — read before attempting PYQs
---
SSC CGL and other exams ask percentage questions in these forms:
1. Direct calculation — 'What is 35% of 480?'
2. Finding the base — '25% of what number is 75?'
3. Percentage increase or decrease — 'A number increases from 80 to 100.
What is the % increase?'
4. Expressing one quantity as a percentage of another — 'What % is 45 of 180?'
5. Finding a number when its percentage value is known.
Formula for % Change:
% Change = [(New Value - Old Value) / Old Value] x 100
If result is positive = % Increase. If negative = % Decrease.
---
ShortcutsUse these to save 30–60 seconds per question
Trick 2 — Percentage of Percentage Shortcut
X% of Y = Y% of X
Example: 16% of 25 = 25% of 16 = 4. Much easier!
Trick 3 — Quick % Calculation:
To find any % quickly, break it into easy parts
Example
17.5% of 400
= 10% of 400 + 5% of 400 + 2.5% of 400
= 40 + 20 + 10 = 70
This avoids long multiplication.
---
Worked ExampleSolve this step-by-step before moving on
1
Step 1
Recognise that 37.5% = 3/8 (memorised fraction)
2
Step 2
Apply: (3/8) x 960
3
Step 3
960 / 8 = 120
4
Step 4
120 x 3 = 360
Answer: 360
Time taken using trick: 8 seconds. Using multiplication: 40+ seconds.
---
WORKED EXAMPLE 2 ---
Question: A number is increased from 240 to 300. What is the percentage increase?
1
Step 1
Find the increase = 300 - 240 = 60
2
Step 2
Apply formula: % Increase = (60 / 240) x 100
3
Step 3
Simplify: 60/240 = 1/4
4
Step 4
1/4 x 100 = 25%
Answer: 25% increase
Key Note: The BASE is always the ORIGINAL (OLD) value, not the new value.
---
Exam TrapsCommon mistakes students make — avoid these
(THE NUMBER 1 TRAP) ---
Trap: Students use the WRONG BASE when calculating % increase or decrease.
Wrong thinking: 'The number changed from 80 to 100, so increase is 20, base is 100.'
Right thinking: 'Base is always the ORIGINAL number, which is 80.'
Wrong answer: (20/100) x 100 = 20%
Correct answer: (20/80) x 100 = 25%
This single mistake causes 2-3 wrong answers per paper. Never forget: ORIGINAL = BASE.
Key Points to Remember
Percentage means 'per hundred' — always a comparison out of 100.
Formula: Percentage = (Part / Whole) x 100.
To find the Part: Part = (Percentage / 100) x Whole.
To find the Whole (base): Whole = (Part x 100) / Percentage.
Shortcut: X% of Y = Y% of X. Use whichever is easier to calculate.
% Change Formula: [(New Value - Old Value) / Old Value] x 100.
Base in % increase/decrease is ALWAYS the original (old) value, never the new value.
A book's price is reduced from ₹500 to ₹400. What is the percentage decrease?
Practice 2easy
A student scored 72 marks out of 120 in an exam. What is his percentage score?
Practice 3easy
A shopkeeper marks an item at ₹500. He offers a 20% discount. What is the selling price?
Practice 4easy
A student scored 72% in an exam and obtained 360 marks. What were the total marks?
Practice 5easy
In an exam, 65% of students passed. If 260 students passed, how many students took the exam?
Practice 6easy
A shirt costs ₹800. Its price is increased by 20%. What is the new price?
Practice 7easy
If 15% of a number is 45, what is the number?
Practice 8easy
What is 25% of 480?
Practice 9easy
A shopkeeper marks the price of an item at ₹500. He offers a discount of 12% on the marked price. What is the selling price of the item?
Practice 10easy
In a class of 80 students, 35% are girls. How many boys are there in the class?
Practice 11easy
If 45% of a number is 360, what is 25% of that number?
Practice 12medium
A shopkeeper marks an item at ₹500. He offers a discount of 12% on the marked price. What is the selling price?
Practice 13medium
A number is increased by 30%, and then the result is decreased by 30%. Is the final number greater than, less than, or equal to the original number?
Practice 14medium
A number is increased by 25%, and then the result is decreased by 20%. What is the net percentage change from the original number?
Practice 15medium
A shopkeeper marks up the cost price of an item by 40%. He then offers a discount of 10% on the marked price. If the cost price is ₹500, what is his profit percentage?
Practice 16medium
In an examination, a student scored 72% marks and obtained 360 marks. What are the total marks of the examination?
Practice 17medium
The price of a commodity increases by 25% and then decreases by 20%. What is the net percentage change in the price?
Practice 18medium
A student's marks increased from 45 to 54. What is the percentage increase in marks?
Practice 19medium
A shopkeeper buys goods for ₹800 and sells them at a profit of 35%. What is the selling price?
Practice 20medium
In an examination, 65% of students passed. If 455 students passed, how many students appeared in total?
8 more practice questions in the Study Panel
Difficulty-graded, bookmarkable, with timed mode. Free account — no credit card.