Half Subtractor MCQ Quiz - Objective Question with Answer for Half Subtractor - Download Free PDF

Last updated on Apr 22, 2025

Latest Half Subtractor MCQ Objective Questions

Half Subtractor Question 1:

For a binary half subtractor having two inputs A and B, the correct set of logical expressions for the outputs D (difference) and X (borrow) is

  1. D = AB + A, X = A
  2. D = A + B + A, X = A
  3. D = B + A, X = B
  4. D = AB + A̅B, X = AB̅

Answer (Detailed Solution Below)

Option 3 : D = B + A, X = B

Half Subtractor Question 1 Detailed Solution

The correct option is 3

Concept:

Truth Table for half subtractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Difference=AB=AB¯+A¯B

Borrow=X=A¯B

Half Subtractor Question 2:

Half Subtractors require _____ bits.

  1. 1
  2. 2
  3. 3
  4. 4

Answer (Detailed Solution Below)

Option 2 : 2

Half Subtractor Question 2 Detailed Solution

Concept:

half subtractor is a combinational circuit that is used to perform the subtraction of two single-bit words, i.e. it requires 2 input bits.

It subtracts two single-bits A & B and produces difference d & borrow b

The equation for half subtractor is :

d = A'B + AB' or A ⊕ B

b = A'B

Truth Table for half subtractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Circuit Diagram:

3 feb

Half Subtractor Question 3:

For a binary half-subtractor having two inputs A and B, the correct set of logical expression for the outputs D (= A minus B) and X (= borrow) are

  1. D=AB+AB¯,X=A¯B
  2. D=AB¯+AB¯,X=AB¯
  3. D=AB¯+A¯B,X=A¯B
  4. D=AB+AB¯,X=AB¯

Answer (Detailed Solution Below)

Option 3 : D=AB¯+A¯B,X=A¯B

Half Subtractor Question 3 Detailed Solution

Truth Table for half substractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Difference=AB=AB¯+A¯B

Borrow=X=A¯B

Half Subtractor Question 4:

Find the Boolean expression for Borrow (B) as the circuit shown below

EC Digital Electronic Subject Test 1 Images-Q16

  1. p¯q+p¯r+qr

  2. pq+pr+qr

  3. pq¯+pr+q¯r

  4. pq¯+p¯r+q¯r

Answer (Detailed Solution Below)

Option 3 :

pq¯+pr+q¯r

Half Subtractor Question 4 Detailed Solution

obtain truth table for above circuit we get

q

r

p

 

 

D

B

0

0

0

 

 

0

0

0

0

1

 

 

1

1

0

1

0

 

 

1

1

0

1

1

 

 

0

1

1

0

0

 

 

1

0

1

0

1

 

 

0

0

1

1

0

 

 

0

0

1

1

1

 

 

1

1


Obtain k – map for B

EC Digital Electronic Subject Test 1 Images-Q16.1

B=q¯p+rp+q¯r=pq¯+pr+q¯r

Top Half Subtractor MCQ Objective Questions

For a binary half-subtractor having two inputs A and B, the correct set of logical expression for the outputs D (= A minus B) and X (= borrow) are

  1. D=AB+AB¯,X=A¯B
  2. D=AB¯+AB¯,X=AB¯
  3. D=AB¯+A¯B,X=A¯B
  4. D=AB+AB¯,X=AB¯

Answer (Detailed Solution Below)

Option 3 : D=AB¯+A¯B,X=A¯B

Half Subtractor Question 5 Detailed Solution

Download Solution PDF

Truth Table for half substractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Difference=AB=AB¯+A¯B

Borrow=X=A¯B

For a binary half subtractor having two inputs A and B, the correct set of logical expressions for the outputs D (difference) and X (borrow) is

  1. D = AB + A, X = A
  2. D = A + B + A, X = A
  3. D = B + A, X = B
  4. D = AB + A̅B, X = AB̅

Answer (Detailed Solution Below)

Option 3 : D = B + A, X = B

Half Subtractor Question 6 Detailed Solution

Download Solution PDF

The correct option is 3

Concept:

Truth Table for half subtractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Difference=AB=AB¯+A¯B

Borrow=X=A¯B

Half Subtractor Question 7:

For a binary half-subtractor having two inputs A and B, the correct set of logical expression for the outputs D (= A minus B) and X (= borrow) are

  1. D=AB+AB¯,X=A¯B
  2. D=AB¯+AB¯,X=AB¯
  3. D=AB¯+A¯B,X=A¯B
  4. D=AB+AB¯,X=AB¯

Answer (Detailed Solution Below)

Option 3 : D=AB¯+A¯B,X=A¯B

Half Subtractor Question 7 Detailed Solution

Truth Table for half substractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Difference=AB=AB¯+A¯B

Borrow=X=A¯B

Half Subtractor Question 8:

Half Subtractors require _____ bits.

  1. 1
  2. 2
  3. 3
  4. 4

Answer (Detailed Solution Below)

Option 2 : 2

Half Subtractor Question 8 Detailed Solution

Concept:

half subtractor is a combinational circuit that is used to perform the subtraction of two single-bit words, i.e. it requires 2 input bits.

It subtracts two single-bits A & B and produces difference d & borrow b

The equation for half subtractor is :

d = A'B + AB' or A ⊕ B

b = A'B

Truth Table for half subtractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Circuit Diagram:

3 feb

Half Subtractor Question 9:

For a binary half subtractor having two inputs A and B, the correct set of logical expressions for the outputs D (difference) and X (borrow) is

  1. D = AB + A, X = A
  2. D = A + B + A, X = A
  3. D = B + A, X = B
  4. D = AB + A̅B, X = AB̅

Answer (Detailed Solution Below)

Option 3 : D = B + A, X = B

Half Subtractor Question 9 Detailed Solution

The correct option is 3

Concept:

Truth Table for half subtractor:

A B Difference Borrow
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

 

Difference=AB=AB¯+A¯B

Borrow=X=A¯B

Half Subtractor Question 10:

Find the Boolean expression for Borrow (B) as the circuit shown below

EC Digital Electronic Subject Test 1 Images-Q16

  1. p¯q+p¯r+qr

  2. pq+pr+qr

  3. pq¯+pr+q¯r

  4. pq¯+p¯r+q¯r

Answer (Detailed Solution Below)

Option 3 :

pq¯+pr+q¯r

Half Subtractor Question 10 Detailed Solution

obtain truth table for above circuit we get

q

r

p

 

 

D

B

0

0

0

 

 

0

0

0

0

1

 

 

1

1

0

1

0

 

 

1

1

0

1

1

 

 

0

1

1

0

0

 

 

1

0

1

0

1

 

 

0

0

1

1

0

 

 

0

0

1

1

1

 

 

1

1


Obtain k – map for B

EC Digital Electronic Subject Test 1 Images-Q16.1

B=q¯p+rp+q¯r=pq¯+pr+q¯r

Half Subtractor Question 11:

Let the Number of NAND gates required to Generated Half adder is x and Number of NOR gates required to Generated a full adder is y. Then find the value of 2x+y= 

Answer (Detailed Solution Below) 19

Half Subtractor Question 11 Detailed Solution

Number of (NAND (or) NOR) gates required to implement (Half adder (or) Half subtractor) = 5 = x

No of NAND (or) NOR required to implement full adder (or) full subtractor = 9 = y

∴ 2x + y = 19

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