Number Conversion for SSC CGL, Know How to Convert Binary to Decimal

Are you preparing for SSC CGL 2025 exam? Then you should also prepare the number conversion for SSC CGL 2025 Tier 1 exam. Number conversion means converting the binary to decimal, decimal to hexadecimal, and vice versa. This blog has provided the basic concept of the number conversion with some questions that match the level of the exam. Along with that, a PDF is provided having a detailed solution for the questions that we have provided. Go through this blog carefully and boost your preparation level.

Basic Concept of Number Conversion for SSC CGL

Number conversion refers to converting a number from one number system (or base) to another. It’s crucial for understanding how computers work and is a part of many aptitude tests like SSC CGL.

Types of Number Systems

There are four commonly used number systems:

A. Binary to Decimal

Multiply each binary digit by 2n2^n2n (where n is the position index from right, starting with 0), then add all.

Example: Convert 1011₂​ to decimal.

1×23+0×22+1×21+1×20=8+0+2+1=11

B. Decimal to Binary

Divide the decimal number by 2, note the remainder, repeat till the quotient is 0, then reverse the remainders.

Example: Convert 13₁₀​ to binary.

13 ÷ 2 = 6, remainder 1
6 ÷ 2 = 3, remainder 0
3 ÷ 2 = 1, remainder 1
1 ÷ 2 = 0, remainder 1

Answer: 1101

C. Decimal to Octal

Divide by 8 and reverse the remainders.

Example: Convert 65₁₀ to octal.

65 ÷ 8 = 8, remainder 1
8 ÷ 8 = 1, remainder 0
1 ÷ 8 = 0, remainder 1

Answer: 101₈

D. Octal to Decimal

Method: Multiply each digit by powers of 8.

Example: Convert 157₈​ to decimal.

1×8²+5×8¹+7×8⁰=64+40+7=111

Answer: 111

E. Decimal to Hexadecimal

Divide the number by 16, reverse the remainders. Use A–F for 10–15.

Example: Convert 254₁₀​ to hexadecimal.

254 ÷ 16 = 15, remainder 14 → E
15 ÷ 16 = 0, remainder 15 → F

Answer: FE₁₆

F. Hexadecimal to Decimal

Multiply each digit by powers of 16.

Example: Convert 1A₁₆​ to decimal.

1×161+10×160=16+10=26

Answer: 26

G. Binary to Octal / Hexadecimal

Group binary digits in sets of 3 (octal) or 4 (hex) from the right.

Example (Binary to Octal): Convert 110101₂​ to octal.

Group: 110 101
110 = 6, 101 = 5 → 65₈

Answer: 65

Number Conversion Questions for SSC CGL: Download Free PDF

Here we have provided the questions on number conversion for SSC CGL exam. Along with that, we have provided a PDF containing solutions to these questions. Practice these questions and analyze the difficulty level of the questions. Before that, you are strongly advised to know the basics of the topic and understand it. It will help you to solve these questions easily.

1. Convert (611)₁₀ into binary.

(1) (1001011111)₂

(2) (1001100111)₂

(3) (1001110011)₂

(4) (1001100011)₂

2. Convert (10110110)₂ into decimal.

(1) (178)₁₀

(2) (179)₁₀

(3) (182)₁₀

(4) (183)₁₀

3. Convert (11D)₁₆ into decimal.

(1) (283)₁₀

(2) (284)₁₀

(3) (285)₁₀

(4) (286)₁₀

4. Find the sum of (1001)₂ and (1011)₂.

(1) (10000)₂

(2) (10100)₂

(3) (10101)₂

(4) (11001)₂

5. Convert (101110)₂ into hexadecimal.

a) (28)₁₆

b) (29)₁₆

c) (2E)₁₆

d) (2F)₁₆

6. Convert (251)₈ into binary.

(1) (11101001)₂

(2) (10101001)₂

(3) (01010101)₂

(4) (11100011)₂

7. Convert (101011)₂ into octal.

(1) (51)₈

(2) (49)₈

(3) (53)₈

(4) (57)₈

8. Convert (119)₁₆ into octal.

(1) (411)₈

(2) (431)₈

(3) (435)₈

(4) (429)₈

9. Convert (79)₈ into hexadecimal.

(1) (4F)₁₆

(2) (5F)₁₆

(3) (67)₁₆

(4) (57)₁₆

10. Convert (27.125)₁₀ into binary.

(1) (11011.101)₂

(2) (11011.010)₂

(3) (11011.011)₂

(4) (11011.001)₂

Additional Resources for SSC CGL 2025 Exam Preparation

Here, we have provided some free preparation resources that will help you in your revision and exam preparation. Just don’t focus only on solving the number conversion questions. You are strongly advised to focus on other topics also. You are strongly advised to attempt these resources by making a plan so that you can use these resources systematically and effectively.

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FAQs: Number Conversion for SSC CGL

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