This page covers SSC GD Constable Basic Percentage with complete concept notes, 16 graded practice MCQs, key points and exam-specific tips. Free to study.
Core ConceptRead this first — the foundation of the topic
Basic Percentage is the foundation of all percentage problems in SSC CGL. It measures parts per hundred. The word 'percent' comes from Latin 'per centum' meaning 'by hundred'. Understanding this concept is crucial as it appears in 2-3 questions in every SSC CGL paper. Core Concept: Percentage is a way to express a fraction with denominator 100. When you say 25%, it means 25 out of 100 parts. Think of it as cutting a pie into 100 equal slices and taking some of them.
Key RulesCore rules you must know cold
First, percentage is always calculated on a base value. Second, 100% means the complete quantity. Third, percentages can exceed 100% when the part is larger than the whole. Fourth, percentage change and percentage of a number are different concepts.
Formula BlockMemorise — at least one formula appears in every paper
• Percentage = (Part/Whole) × 100
• Part = (Percentage/100) × Whole
• Whole = (Part × 100)/Percentage
• Percentage to Fraction: x% = x/100
• Percentage to Decimal: x% = x/100 = 0.0x
Exam PatternsWhat examiners ask — read before attempting PYQs
Powerful Shortcuts for Quick Calculation
Shortcut 1 - Common Percentage Conversions:
• 50% = 1/2, 25% = 1/4, 20% = 1/5, 10% = 1/10
• 33.33% = 1/3, 66.67% = 2/3, 12.5% = 1/8, 16.67% = 1/6
Memorize these to solve faster without calculations
Shortcut 2 - Quick Mental Math Trick
• For 15% of any number: Take 10% + 5%
• For 35% of any number: Take 30% + 5%
• Break complex percentages into easier chunks
Worked ExampleSolve this step-by-step before moving on
1
Step 1
Convert percentage to decimal: 24% = 24/100 = 0.24
Add: 170 + 34 = 204
Answer: 24% of 850 = 204
Worked Example 2: What percentage is 156 of 240?
1
Step 1
Use formula: Percentage = (Part/Whole) × 100
2
Step 2
Substitute values: (156/240) × 100
3
Step 3
Simplify fraction: 156/240 = 13/20 (dividing by 12)
4
Step 4
Convert to decimal: 13/20 = 0.65
5
Step 5
Multiply by 100: 0.65 × 100 = 65%
Answer: 156 is 65% of 240
Shortcut 3 - The Unitary Method for Percentages:
If x% = y, then 1% = y/x, and 100% = (y × 100)/x
This eliminates complex calculations in competitive exams.
Exam TrapsCommon mistakes students make — avoid these
- The #1 Trap: Students confuse 'percentage of' with 'percentage more than'. For example, if A is 20% of B, it does NOT mean A is 20% more than B. '20% of B' means A = 0.20 × B. But '20% more than B' means A = B + 0.20 × B = 1.20 × B.
This confusion costs precious marks in exams.
Another frequent error is forgetting to convert percentage back to the required form. Always check if the answer needs to be in percentage, decimal, or fraction format.
Key Points to Remember
Percentage means parts per hundred, always calculated on a base value
A shopkeeper sells an item for ₹480, which is 20% more than the cost price. What is the cost price?
Practice 3easy
What percentage of 500 is 125?
Practice 4easy
A student scored 72 marks out of 120 in an exam. What is the percentage score?
Practice 5easy
If the price of an item decreases by 30%, and the new price is ₹420, what was the original price?
Practice 6medium
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?
Practice 7medium
In an examination, 65% of students passed. If 390 students passed, how many students appeared in total?
Practice 8medium
A student scored 72% in Mathematics and 68% in English. If Mathematics carries 80 marks and English carries 100 marks, what is the overall percentage score?
Practice 9medium
The price of a commodity increases by 15%. By what percentage should the consumption be reduced so that the expenditure remains the same?
Practice 10medium
A person's salary is increased from ₹24,000 to ₹27,600. What is the percentage increase in salary?
Practice 11hard
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 is ₹800, what is his profit percentage?
Practice 12hard
In an election, candidate A received 45% of votes and candidate B received 35% of votes. The remaining votes were invalid. If the total number of votes cast was 8000, how many more votes did A receive than B?
Practice 13hard
A number is increased by 20%, then the result is decreased by 20%. What is the net change in the original number as a percentage?
Practice 14hard
A student scored 72% in English and 68% in Mathematics. If English has a weightage of 40% and Mathematics has a weightage of 60%, what is the student's overall percentage?
Practice 15hard
The price of a commodity increases by 15% in the first year and then decreases by 10% in the second year. If the final price is ₹5175, what was the original price?
Practice 16hard
A person spends 30% of his income on rent, 25% on food, and 15% on transport. The remaining amount is ₹9000. What is his total monthly income?
60-Second Revision — Basic Percentage
Remember: Percentage = (Part/Whole) × 100 for all basic problems
Formula: Part = (Percentage/100) × Whole for finding quantities
Trap: 'x% of y' ≠ 'x% more than y' - completely different meanings
Shortcut: Use fraction conversions (25% = 1/4) for faster calculations
Quick check: 50% should always give exactly half the original number