📘 Introduction
Mathematics is a key scoring subject in competitive exams like OSSSC, SSC, Banking, and Railway exams. Questions are commonly asked from topics such as number system, percentage, profit and loss, ratio, and simple arithmetic. These questions test your calculation ability, speed, and accuracy.
Practicing MCQs regularly helps in improving problem-solving skills and time management. This set of questions is designed with simple explanations so that you can understand the concepts easily. With regular practice, you can score high marks in the mathematics section.
📝 Mathematics MCQs (With Explanation)
🔹 Section 1: Number System
Q1. What is the smallest prime number?
A. 0
B. 1
C. 2
D. 3
Answer: C
Explanation: 2 is the smallest prime number and the only even prime number.
Q2. Which number is divisible by 3?
A. 124
B. 135
C. 142
D. 158
Answer: B
Explanation: Sum of digits of 135 = 1+3+5 = 9, which is divisible by 3.
Q3. LCM of 4 and 6 is?
A. 12
B. 24
C. 6
D. 18
Answer: A
Explanation: Multiples of 4 and 6 → common smallest = 12.
Q4. HCF of 12 and 18 is?
A. 6
B. 3
C. 9
D. 12
Answer: A
Explanation: Common factors → 1, 2, 3, 6 → highest is 6.
Q5. Which is a perfect square?
A. 18
B. 20
C. 25
D. 27
Answer: C
Explanation: 25 = 5 × 5, so it is a perfect square.
👉 Exam Tip: Questions on LCM, HCF, and divisibility are frequently asked.
🔹 Section 2: Percentage
Q6. 25% of 200 is?
A. 25
B. 50
C. 75
D. 100
Answer: B
Explanation: 25% of 200 = (25/100) × 200 = 50.
Q7. Increase 100 by 20% = ?
A. 110
B. 120
C. 130
D. 140
Answer: B
Explanation: 20% of 100 = 20 → total = 120.
Q8. Decrease 500 by 10% = ?
A. 450
B. 400
C. 480
D. 490
Answer: A
Explanation: 10% of 500 = 50 → 500 − 50 = 450.
Q9. What percent is 50 of 200?
A. 10%
B. 20%
C. 25%
D. 30%
Answer: C
Explanation: (50/200) × 100 = 25%.
Q10. 40% of 150 = ?
A. 50
B. 60
C. 70
D. 80
Answer: B
Explanation: (40/100) × 150 = 60.
👉 Quick Tip: Learn percentage formulas for faster solving.
🔹 Section 3: Arithmetic
Q11. If CP = 100, SP = 120, profit = ?
A. 10
B. 20
C. 30
D. 40
Answer: B
Explanation: Profit = SP − CP = 120 − 100 = 20.
Q12. Ratio of 10:20 simplifies to?
A. 1:2
B. 2:1
C. 5:10
D. 10:1
Answer: A
Explanation: Divide both by 10 → 1:2.
Q13. Average of 2, 4, 6 = ?
A. 3
B. 4
C. 5
D. 6
Answer: B
Explanation: (2+4+6)/3 = 4.
Q14. 12 × 8 = ?
A. 96
B. 84
C. 88
D. 92
Answer: A
Explanation: 12 multiplied by 8 = 96.
Q15. 100 ÷ 4 = ?
A. 20
B. 25
C. 30
D. 40
Answer: B
Explanation: 100 divided by 4 = 25.
👉 Exam Tip: Arithmetic basics are easy marks if practiced.
🔹 Section 4: Mixed Questions
Q16. Square root of 81 = ?
A. 7
B. 8
C. 9
D. 10
Answer: C
Explanation: 9 × 9 = 81.
Q17. Cube of 3 = ?
A. 6
B. 9
C. 27
D. 81
Answer: C
Explanation: 3 × 3 × 3 = 27.
Q18. 15% of 80 = ?
A. 10
B. 12
C. 14
D. 16
Answer: B
Explanation: (15/100) × 80 = 12.
Q19. If 5x = 25, then x = ?
A. 3
B. 4
C. 5
D. 6
Answer: C
Explanation: Divide both sides by 5 → x = 5.
Q20. 7 + 8 × 2 = ?
A. 30
B. 23
C. 16
D. 20
Answer: B
Explanation: BODMAS rule → 8×2=16 → 16+7=23.
🔑 Key Points Summary
- Number system basics are important
- Percentage formulas save time
- Arithmetic is scoring section
- Practice improves speed
- Learn shortcut methods
- Revise formulas regularly
📌 Conclusion
Mathematics can be one of the highest scoring sections if you focus on basic concepts and practice regularly. Start with simple topics like number system and percentage, then move to arithmetic problems. Use shortcuts and formulas to save time in exams. With consistent practice and revision, you can easily score high marks in the mathematics section.
OSSSC Mathematics – 100 MCQs (My Real Study Notes for RI, ARI, Amin, Forest Guard, CGL)
So, I’ve been preparing Maths for OSSSC exams like RI, ARI, Amin, Forest Guard… and honestly, at first I was really scared of Maths 😅
Like, whenever I saw questions on percentage, profit-loss, time-work… my mind used to go blank.
But after some days of practice, I realized something important:
Maths is not about being smart… it’s about practice + small tricks.
Now I’m not saying I became expert 😄 but yes, I improved a lot. So I’m sharing how I studied, in a simple way.
1. Number System
When I first studied this, I thought it’s very basic. But in MCQs, they twist simple concepts.
What I focused on:
- Even & Odd numbers
- Prime numbers
- Divisibility
My simple trick:
- Even → ends with 0,2,4,6,8
- Prime → only 2 factors
Example:
Is 19 prime?
Check: only divisible by 1 and 19 → yes
My mistake:
I ignored basics, and lost easy marks.
2. Percentage
This topic comes again and again in exams.
At first I used calculator in practice (bad habit 😅), but later I improved mental calculation.
Easy tricks I use:
- 50% = half
- 25% = 1/4
- 10% = divide by 10
Example:
25% of 200 = 50
Real-life example:
When we see “30% discount” in shop, we quickly calculate. Same concept here.
3. Profit & Loss
This topic confused me a lot in beginning.
Basic idea:
- CP → Cost Price
- SP → Selling Price
My trick:
- Profit → SP > CP
- Loss → CP > SP
Example:
Bought for 100, sold for 80 → loss = 20
4. Simple Interest
This is formula based, but not difficult.
Formula:
SI = (P × R × T) / 100
My trick:
Understand meaning instead of mugging.
- P = money
- R = rate
- T = time
Example:
P=1000, R=10%, T=2 → SI=200
5. Ratio & Proportion
Earlier I found this confusing.
But then I simplified it.
Basic idea:
Comparison between numbers.
Example:
4:8 = 1:2
My trick:
Always reduce to simplest form.
6. Time & Work
This topic looked tough, but actually logical.
Simple idea:
- More people → less time
- Less people → more time
Example:
If 1 person does work in 8 days
Then 2 persons → 4 days
My realization:
Think practically, not just formula.
7. Average
This is easy and scoring.
Formula:
Average = Total / Number
Example:
10, 20, 30 → Average = 20
Tip:
Be careful in calculation.
8. Mensuration
This is about shapes and formulas.
Important shapes:
- Square
- Rectangle
- Circle
My trick:
Learn only basic formulas.
Example:
Area of rectangle = length × breadth
How I Practice MCQs
Earlier I just read formulas, but forgot in exam.
Now I do:
- Learn concept
- Solve MCQs
- Check mistakes
- Revise
This improved my score.
Sample MCQs
1. 50% of 300 = ?
Answer: 150
2. CP=200, SP=250 → profit?
Answer: 50
3. SI of 1000 at 10% for 1 year?
Answer: 100
4. Ratio 6:12 = ?
Answer: 1:2
5. Average of 5,10,15?
Answer: 10
6. Area of square (side 5)?
Answer: 25
Mistakes I Made
1. Not practicing enough
Maths needs practice daily.
2. Fear of formulas
But they are simple.
3. Calculation mistakes
Lost marks in easy questions.
One Small Insight
Maths is not difficult.
We make it difficult by overthinking.
One Relatable Example
Sometimes I knew the method, but made small calculation mistake and got wrong answer.
Now I double-check before marking.
My Personal Tips
1. Practice daily
Even 20 questions help.
2. Focus on basics
Strong base is important.
3. Revise formulas
Very important.
4. Stay calm
Don’t panic in exam.
Final Thoughts
For OSSSC exams, Maths is not very tough.
But you need speed and accuracy.
Just remember:
- Practice regularly
- Learn shortcuts
- Revise formulas
Even 1 hour daily is enough.
MCQ Practice Rules
- Read question carefully
- Don’t rush
- Check calculations
- Revise mistakes
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