SSC CHSL 2027 Mathematical Operations: Rules, Tricks & Practice Questions

Mathematical Operations is an important topic in reasoning preparation for competitive examinations. These questions test your ability to understand mathematical symbols, apply operations correctly and identify relationships between numbers.

For SSC CHSL 2027, candidates should practise questions based on symbol interchange, replacing signs, finding correct equations and applying basic mathematical operations. This guide covers the main concepts, solving methods and practice MCQs.

1. What Are Mathematical Operations Questions?

In mathematical operations questions, candidates are given numbers and mathematical signs. They must follow the given conditions to find the correct answer or identify the equation that becomes correct after changing the signs.

Example:

If + means × and × means +, find the value of 4 + 3 × 2.

Solution: Replace the signs according to the instructions.

4 × 3 + 2 = 12 + 2 = 14

Answer: 14

2. Important Types of Mathematical Operations

A. Interchanging Mathematical Signs

In these questions, two or more mathematical signs are interchanged. You must replace the original signs and calculate the result.

Example: If + and − are interchanged, evaluate 15 + 5 − 3.

After interchange: 15 − 5 + 3 = 13

B. Replacing Symbols with Operations

Sometimes symbols are assigned specific mathematical meanings. Apply the given meanings before calculating.

Example: If @ means + and # means ×, find 3 # 4 @ 2.

After replacement: 3 × 4 + 2 = 14

C. Making an Equation Correct

These questions ask you to interchange signs or numbers so that the given equation becomes mathematically correct.

Example: Which interchange of signs makes this equation correct?

8 + 4 × 2 = 16

Interchange + and ×: 8 × 4 + 2 = 34. This does not satisfy the equation, so the proposed interchange is incorrect. Always verify the complete equation before selecting an option.

D. Finding the Missing Value

Some questions provide an incomplete mathematical expression. Use the given operations to calculate the missing number.

Example: 12 ÷ 3 + ? = 9

4 + ? = 9, therefore Answer: 5

3. Rules and Tricks to Solve Questions

• Read the instructions: Understand which symbols or signs have been changed.
• Replace the signs first: Do not calculate using the original meanings.
• Follow BODMAS: Apply brackets, orders, division, multiplication, addition and subtraction in the correct order.
• Check both sides: For equation questions, verify that the left-hand side equals the right-hand side.
• Avoid mental mistakes: Write the changed expression before calculating.
• Verify the answer: Substitute the selected option and check the result.

4. Solved Examples

Example 1: If + means ÷ and ÷ means +, find 20 + 5 ÷ 3.

Solution: Replace the signs: 20 ÷ 5 + 3 = 4 + 3.

Answer: 7

Example 2: If × means − and − means ×, find 10 × 3 − 2.

Solution: Replace the signs: 10 − 3 × 2 = 10 − 6.

Answer: 4

Example 3: Find the missing number: 18 ÷ 3 + ? = 10.

Solution: 6 + ? = 10.

Answer: 4

5. SSC CHSL 2027 Mathematical Operations Practice Questions

Choose the correct option for each question.

Q1. If + means × and × means +, find 5 + 2 × 3.

A. 13
B. 15
C. 17
D. 20

Q2. If − and + are interchanged, find the value of 20 + 8 − 4.

A. 8
B. 12
C. 16
D. 24

Q3. If ÷ means × and × means ÷, find 24 ÷ 4 × 2.

A. 3
B. 8
C. 12
D. 24

Q4. If @ means − and # means +, find 15 @ 5 # 3.

A. 7
B. 10
C. 13
D. 17

Q5. Find the missing number: 16 ÷ 4 + ? = 9.

A. 3
B. 4
C. 5
D. 6

Q6. If + means ÷ and − means ×, find 18 + 3 − 2.

A. 6
B. 9
C. 12
D. 15

Q7. If × means + and + means −, find 14 × 6 + 5.

A. 13
B. 15
C. 20
D. 25

Q8. Which sign should replace the question mark to make the equation correct? 12 ? 3 = 4

A. +
B. −
C. ×
D. ÷

Q9. If − means ÷ and ÷ means −, find 18 − 3 ÷ 2.

A. 3
B. 4
C. 5
D. 6

Q10. If + means − and − means +, find 25 + 10 − 5.

A. 10
B. 15
C. 20
D. 30

Answer Key with Explanations

6. Preparation Tips for SSC CHSL 2027

• Revise basic mathematical operations and BODMAS.
• Practise sign interchange questions regularly.
• Learn to replace symbols carefully before calculation.
• Practise simple equations and missing-value problems.
• Check every step to avoid calculation errors.
• Attempt timed reasoning practice sets to improve speed and accuracy.

Prepare for SSC CHSL 2027 with Katara Academy

Mathematical Operations questions become easier when you understand the meaning of each symbol and apply the correct calculation rules. Practise different question types regularly to strengthen your reasoning skills.

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