**Digital Circuits Questions and Answers – BCD Adder**

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “BCD Adder”.

**1. The decimal number system represents the decimal number in the form of ____________**

a) Hexadecimal

b) Binary coded

c) Octal

d) Decimal

**Answer:**b

**Explanation:**Binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Hexadecimal and Octal are number systems having base 16 and 8 respectively.

**2. 2 ^{9} input circuit will have total of ____________**

a) 32 entries

b) 128 entries

c) 256 entries

d) 512 entries

**Answer**: d

**Explanation**: 2

^{9}input circuit would have 512(2*2*2*2*2*2*2*2*2 = 512) entries.

**3. BCD adder can be constructed with 3 IC packages each of ____________**

a) 2 bits

b) 3 bits

c) 4 bits

d) 5 bits

**Answer**: c

**Explanation**: Binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. BCD adder can be constructed with 3 IC packages. Each of 4-bit adders is an MSI(Medium scale Integration) function and 3 gates for the correction logic need one SSI (Small Scale Integration) package.

**4. The output sum of two decimal digits can be represented in ____________**

a) Gray Code

b) Excess-3

c) BCD

d) Hexadecimal

**Answer:**c

**Explanation:**The output sum of two decimal digits can be represented in BCD(Binary-coded decimal). Binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight.

**5. The addition of two decimal digits in BCD can be done through ____________**

a) BCD adder

b) Full adder

c) Ripple carry adder

d) Carry look ahead

**Answer:**a

**Explanation:**The addition of two decimal digits in BCD can be done through BCD adder. Every input inserted, in addition by the user converted into binary and then proceed for the addition. Whereas, Full Adder, Ripple Carry Adder and Carry Look Adder are for the addition of binary bits.

**6. 3 bits full adder contains ____________**

a) 3 combinational inputs

b) 4 combinational inputs

c) 6 combinational inputs

d) 8 combinational inputs

**Answer:**d

**Explanation:**3 bits full adder contains 2

^{3}= 8 combinational inputs.

**7. The simplified expression of full adder carry is ____________**

a) c = xy+xz+yz

b) c = xy+xz

c) c = xy+yz

d) c = x+y+z

**Answer:**a

**Explanation:**A full adder is a combinational circuit having 3 inputs and 2 outputs, namely SUM and CARRY. The simplified expression of full adder carry is c = xy+xz+yz.

**8. Complement of F’ gives back __________**

a) F’

b) F

c) FF

d) FF’

**Answer:**b

**Explanation:**Complement means inversion. So, complement of F’ gives back F, as per the Law of Involution.

**9. Decimal digit in BCD can be represented by ____________**

a) 1 input line

b) 2 input lines

c) 3 input lines

d) 4 input lines

**Answer:**d

**Explanation:**Binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Decimal digit in BCD can be represented by 4 input lines. Since it is constructed with 4-bits.

**10. The number of logic gates and the way of their interconnections can be classified as ____________**

a) Logical network

b) System network

c) Circuit network

d) Gate network

**Answer:** a

**Explanation: **The number of different levels of logic gates is represented in a fashion which is known as a logical network.

**« Prev – Digital Circuits Questions and Answers – Fast Adder & Serial Adder – 2**

**» Next – Digital Circuits Questions and Answers – Combinational Circuits**