Digital Logic MCQ Quiz - Objective Question with Answer for Digital Logic - Download Free PDF

Last updated on Jun 23, 2025

Latest Digital Logic MCQ Objective Questions

Digital Logic Question 1:

147 in base 10 when converted to hexadecimal system will be:

  1. 8B
  2. 9A
  3. 93
  4. 83
  5. None of the above

Answer (Detailed Solution Below)

Option 3 : 93

Digital Logic Question 1 Detailed Solution

Answer: Option 3

Explanation

Step 1: first we convert 147 to the Binary number system.

 BinaryConversion

(147)10 = (10010011)2

Step 2: Now we group 4 bits to convert the Hexadecimal number system.

1001 0011

≡ (93)16

Digital Logic Question 2:

Which of the following codes is also known as reflected binary code?

  1. Excess-3 code
  2. Gray code 
  3. Straight binary code 
  4. Error code
  5. None of the above

Answer (Detailed Solution Below)

Option 2 : Gray code 

Digital Logic Question 2 Detailed Solution

The correct answer is Gray code.

Key Points

  • The Gray code, also referred to as the reflected binary code, is a binary numeral system in which two consecutive numbers differ in only one bit. The unique property of Gray code is that each transition from one value to the next value involves changing only one bit.
  • This system was invented by Frank Gray at Bell Labs to prevent spurious output from electromechanical switches. For instance, while switching from one position to another in standard binary code, there is a risk that switches will change at different times leading to invalid numbers, but with Gray code, since only one bit changes at a time, such misinterpretations are avoided.
  • So, Gray code is also known as reflected binary code because the sequence of binary values reflects it about its midpoint. For example:
  • Binary: 000, 001, 010, 011, 100, 101, 110, 111
  • If we reflect this sequence, i.e., reverse it, we get:111, 110, 101, 100, 011, 010, 001, 000
  • Now let's take the first half of the original sequence and the first half of the reflected sequence.

  • By inverting the bits in the second half, we get the sequence of Gray codes:  000, 001, 011, 010, 110, 111, 101, 100

So, every binary number has a unique Gray code, and vice versa, attributing to why the term "reflected binary code" is used to describe the Gray code.

Digital Logic Question 3:

The decimal equivalent of a binary number 1001110 is: 

  1. 86
  2. 74
  3. 78
  4. 82
  5. None of the above

Answer (Detailed Solution Below)

Option 3 : 78

Digital Logic Question 3 Detailed Solution

Convert binary to decimal :-

  • For binary number with n digits:
  • dn-1 ... d3 d2 d1 d0
  • The decimal number is equal to the sum of binary digits (dn) times their power of 2 (2n):
  • decimal = d0×20 + d1×21 + d2×22 + ...

 

Calculation:

Decimal equivalent of binary number 1001110 :-
=  1 × 2+ 0 x 25 + 0 x 2+ 1 x 2+ 1 x 22 + 1 x 2+ 0 x 20

= 64 + 0 + 0 + 8 + 4 + 2 + 0 = 78​

Digital Logic Question 4:

The binary representation of 129.25 is _____ .

  1. (10000001.01)2
  2. (11000001.01)2
  3. (10000011.10)2
  4. (10000001.11)2
  5. None of the above

Answer (Detailed Solution Below)

Option 1 : (10000001.01)2

Digital Logic Question 4 Detailed Solution

Binary to decimal conversion →

RRB JE CS 10 7Q 26thAug 2015 Shift2 Hindi images Q1a

(129)10 = (10000001)2

0.25 → 0.25 × 2 = 0.5

0.5 × 2 = 1

(0.25)10 = (.01)2

(129.25)10 = (10000001.01)2

Digital Logic Question 5:

2's complement of (1000)2 is

  1. 0001
  2. 0101
  3. 0111
  4. 1000
  5. None of the above

Answer (Detailed Solution Below)

Option 4 : 1000

Digital Logic Question 5 Detailed Solution

2's Complement - It is a type of mathematical and logical (binary) representation that helps in representing signed numbers and performing arithmetic operations such as subtraction, addition, etc.

To perform 2's complement of (1000)2 we will perform the following steps -

  1. We will perform 1's complement on (1000)2 by flipping 1s to 0s and 0s to 1s.
    (1000)2 ===> (0111)2
  2. Now we will add 1 to the resultant value, that is, (0111)2.
    (0111)2 + (1)2 ===> (1000)2
  3. Hence, we get (1000)2 back after 2's complement.

Top Digital Logic MCQ Objective Questions

Binary number 101110110 is equal to decimal number _______.

  1. 468
  2. 412
  3. 374
  4. 326

Answer (Detailed Solution Below)

Option 3 : 374

Digital Logic Question 6 Detailed Solution

Download Solution PDF
  • The correct answer is option 3, i.e., 374.
  • Binary number 101110110 is equal to decimal number 374.
  • Following method can be used to convert Binary number to Decimal number:
  1. (101110110)2 = (1 x 28) + (0 x 27) + (1 x 26) + (1 x 25) + (1 x 24) + (0 x 23) + (1 x 22) + (1 x 21) + (0 x 20)
  2. (101110110)2 = 256 + 0 + 64 + 32 + 16 + 0 + 4 + 2 + 0
  3. (101110110)2 = 374

One megabyte In base 2 (binary) Is equivalent to             .

  1. 103 bytes
  2. 104 bytes
  3. 210 bytes
  4. 220 bytes

Answer (Detailed Solution Below)

Option 4 : 220 bytes

Digital Logic Question 7 Detailed Solution

Download Solution PDF

The correct answer is 220 bytes.

Key Points

  • 1 Megabyte is equal to 1000000 bytes (decimal).
  • 1 MB = 106 B in base 10 (SI).
  • 1 Megabyte is equal to 1048576 bytes (binary).
  • 1 MB = 220 B in base 2.
  • Byte is the basic unit of digital information transmission and storage, used extensively in information technology, digital technology, and other related fields. It is one of the smallest units of memory in computer technology, as well as one of the most basic data measurement units in programming.
  • The earliest computers were made with the processor supporting 1 byte commands, because in 1 byte you can send 256 commands. 1 byte consists of 8 bits,
  • Megabyte (MB) is a unit of transferred or stored digital information, which is extensively used in information and computer technology.
  • In SI, one megabyte is equal to 1,000,000 bytes. At the same time, practically 1 megabyte is used as 220 B, which means 1,048,576 bytes.

625e5fa7f8c06b4efbb09cf9 16544040466351

Binary 110110101 is equal to decimal ________.

  1. 333
  2. 437
  3. 349
  4. 477

Answer (Detailed Solution Below)

Option 2 : 437

Digital Logic Question 8 Detailed Solution

Download Solution PDF

Binary 110110101 is equal to decimal 437

Calculation:

1 1 0 1 1 0 1 0 1

From rightmost first column as follows

=> (20 * 1) + (21 * 0) + (22 * 1) + (23 * 0) + (24 * 1) + (25 * 1) + (26 * 0) + (27 * 1) + (28 * 1)

=> (1) + (0) + (4) + (0) + (16) + (32) + (0) + (128) + (256)

Decimal value =>437

Convert the hexadecimal number C6 to binary number.

  1. 10010110
  2. 11000100
  3. 11000110
  4. 10100110

Answer (Detailed Solution Below)

Option 3 : 11000110

Digital Logic Question 9 Detailed Solution

Download Solution PDF

The correct answer is 11000110

Key Points

  • To convert the hexadecimal number C6 to a binary number, you can convert each hexadecimal digit to its 4-bit binary representation.
  • C in hexadecimal is 12 in decimal, which is 1100 in binary.
  • 6 in hexadecimal is 6 in decimal, which is 0110 in binary.
  • So, the binary representation of C6 is 11000110.

Additional InformationHere are the decimal numbers 1 to 15 represented in both hexadecimal and binary forms:

  • Decimal 1: Hexadecimal 1, Binary 0001
  • Decimal 2: Hexadecimal 2, Binary 0010
  • Decimal 3: Hexadecimal 3, Binary 0011
  • Decimal 4: Hexadecimal 4, Binary 0100
  • Decimal 5: Hexadecimal 5, Binary 0101
  • Decimal 6: Hexadecimal 6, Binary 0110
  • Decimal 7: Hexadecimal 7, Binary 0111
  • Decimal 8: Hexadecimal 8, Binary 1000
  • Decimal 9: Hexadecimal 9, Binary 1001
  • Decimal 10: Hexadecimal A, Binary 1010
  • Decimal 11: Hexadecimal B, Binary 1011
  • Decimal 12: Hexadecimal C, Binary 1100
  • Decimal 13: Hexadecimal D, Binary 1101
  • Decimal 14: Hexadecimal E, Binary 1110
  • Decimal 15: Hexadecimal F, Binary 1111

The sum of two binary numbers 1101111 and 1100101 is ______.

  1. 100011100
  2. 100000110
  3. 11110000
  4. 11010100

Answer (Detailed Solution Below)

Option 4 : 11010100

Digital Logic Question 10 Detailed Solution

Download Solution PDF

The sum of two binary numbers 1101111 and 1100101 is (11010100)2

Note: In Binary addition, 1 + 1 = 10 (0 is sum value and 1 is carry), 1 + 0 = 1, 0 + 1 = 1 and 0 + 0 = 0.

Calculation:

  1    1 1 1 1        (Carry values)

  1 1 0 1 1 1 1     (Binary number 1)

  0    1 0 0 0        (Sum values)

+1 1 0 0 1 0 1     (Binary number 2)

-------------------

1 1 0 1 0 1 0 0    (Answer)

-------------------

The Octal equivalent of the binary number 1011101011 is:

  1. 7353
  2. 1353
  3. 5651
  4. 5657

Answer (Detailed Solution Below)

Option 2 : 1353

Digital Logic Question 11 Detailed Solution

Download Solution PDF

Answer: Option 2

Explanation:

An octal Equivalent of a binary number is obtained by grouping 3 bits from right to left.

001 011 101 011
1 3 5 3


So Octal Equivalent: 1353

Important Points

Binary to Octal code

000

001

010

011

100

101

110

111

0

1

2

3

4

5

6

7

The 8-bit 2's complement form of the number -14 is ______.

  1. 11110010
  2. 00001110
  3. 10001110
  4. 01110001

Answer (Detailed Solution Below)

Option 1 : 11110010

Digital Logic Question 12 Detailed Solution

Download Solution PDF

Calculation:

14 in binary form is represented as:

1410 = (00001110)2

Taking the 1's complement of the above, we get 11110001

Adding 1 to the 1's complement, we get the 2's complement representation of the number, i.e. 11110010

Since there is a 1 in the MSB, the number is a negative number with value -14.

∴ The 2's complement of -6410 contains 7 bits.

Boolean algebra obeys

  1. commutative law only
  2. distributive law only
  3. associative law only
  4. associative, distributive and commutative law

Answer (Detailed Solution Below)

Option 4 : associative, distributive and commutative law

Digital Logic Question 13 Detailed Solution

Download Solution PDF

Name

AND Form

OR Form

Identity law

1.A = A

0 + A = A

Null Law

0.A = 0

1 + A = 1

Idempotent Law

A.A = A

A + A = A

Inverse Law

AA’ = 0

A + A’ = 1

 Commutative Law 

AB = BA

A + B = B + A

Associative Law

(AB)C

 (A + B) + C = A + (B + C) 

Distributive Law

 A + BC = (A + B)(A + C) 

A(B + C) = AB + AC

Absorption Law

A(A + B) = A

A + AB = A

De Morgan’s Law

(AB)’ = A’ + B’

(A + B)’ = A’B’

The number of 1s in the binary representation of (3 ⋆ 4096 + 15 ⋆ 256 + 5 ⋆ 16 + 3) are  

  1. 8
  2. 9
  3. 10
  4. 12

Answer (Detailed Solution Below)

Option 3 : 10

Digital Logic Question 14 Detailed Solution

Download Solution PDF

Application:

Decimal value = (3 ⋆ 4096 + 15 ⋆ 256 + 5 ⋆ 16 + 3)

It can be written as:

(2 + 1) × 212 + (8 + 4 + 2 + 20) × 28 + (4 + 1) × 24  + (2 + 1) × 20

21 × 212 + 20 × 212 + (23 + 22 + 21 + 20) × 28 + (22 + 20) × 24 + (21 + 20) × 20

This can be written as:

213 + 212 + 211 + 210 + 29 × 28 + 26 + 24 + 21 + 20

The binary representation will be:

(11111101010011)2

Which of the following pairs of octal and binary numbers are NOT equal?

  1. (111110111)2 = (767)8
  2. (110110101)2 = (665)8
  3. (10101.11)2 = (25.6)8
  4. (11010)2 = (62)8

Answer (Detailed Solution Below)

Option 4 : (11010)2 = (62)8

Digital Logic Question 15 Detailed Solution

Download Solution PDF

The correct answer is (11010)2 = (62)8

Key Points

Binary numbers and octal numbers are both used in computing. They are different ways of representing the same value - just like how "10" and "ten" are different ways of expressing the same quantity in decimal.

  • Each digit of an octal number represents three binary digits because 23 = 8. Here's the mapping:
    • "000" => "0"
    • "001" => "1"
    • "010" => "2"
    • "011" => "3"
    • "100" => "4"
    • "101" => "5"
    • "110" => "6"
    • "111" => "7"
  • Now let's convert the binary numbers to their equivalent octal numbers.
    • (111 110 111)2 = (7 6 7)8
    • (110 110 101)2 = (6 6 5)8
    • (10 101 . 110)2 = (2 5 . 6)8
    • (11 010)2 = (3 2)8 - Corrupted as the corresponding octal number should be (32)8 instead of (62)8.

Therefore, the 4th pair, (11010)2 = (62)8, is not equal.

Get Free Access Now
Hot Links: online teen patti real money happy teen patti all teen patti game teen patti master game