# Digital Circuits Questions and Answers – 1’s, 2’s, 9’s & 10’s Complements – 2

This set of Digital Electronic Circuits Interview Questions and Answers focuses on “1’s,2’s,9’s & 10’s Complements-2”.

1. If the number of bits in the sum exceeds the number of bits in each added numbers, it results in _________
a) Successor
b) Overflow
c) Underflow
d) Predecessor

Explanation: If the number of bits in the sum exceeds the number of bits in each added numbers, it results in overflow and is also known as excess-one. In case of any arithmetic operation, if the result has less number of bits than the operands, then it is known as underflow condition.

2. An overflow is a _________
a) Hardware problem
b) Software problem
c) User input problem
d) Input Output Error

Explanation: An overflow is a software problem which occurs when the processor cannot handle the result properly when it produces an out of the range output.

3. An overflow occurs in _________
a) MSD position
b) LSD position
c) Middle position
d) Signed Bit

Explanation: An overflow occurs at Most Significant Digit position. It occurs when the processor cannot handle the result properly when it produces an out of the range output.

4. Logic circuitry is used to detect _________
a) Underflow
b) MSD
c) Overflow
d) LSD

Explanation: To check the overflow logic circuitry is used in each case. Overflow occurs when the processor cannot handle the result properly when it produces an out of the range output.

5. 1’s complement can be easily obtained by using _________
a) Comparator
b) Inverter
d) Subtractor

Explanation: With the help of inverter the 1’s complement is easily obtained. Since, during the operation of 1’s complement 1 is converted into 0 and vice-versa and this is well suited for the inverter.

6. The advantage of 2’s complement system is that _________
a) Only one arithmetic operation is required
b) Two arithmetic operations are required
c) No arithmetic operations are required
d) Different Arithmetic operations are required

Explanation: The advantage of 2’s complement is that only one arithmetic operation is required for 2’s complement’s operation and that is only addition. Just by adding a 1 bit to 1’s complement, we get 2’s complement.

7. The 1’s complements requires _________
a) One operation
b) Two operations
c) Three operations
d) Combined Operations

Explanation: Only one operation is required for 1’s complement operation. This includes only inversion of 1’s to 0’s and 0’s to 1’s.

8. Which one is used for logical manipulations?
a) 2’s complement
b) 9’s complement
c) 1’s complement
d) 10’s complement

Explanation: For logical manipulations 1’s complement is used, as all logical operations take place with binary numbers.

9. For arithmetic operations only _________
a) 1’s complement is used
b) 2’s complement
c) 10’s complement
d) 9’s complement

Explanation: Only 2’s complement is used for arithmetic operations, as it is more fast.

10. The addition of +19 and +43 results as _________ in 2’s complement system.
a) 11001010
b) 101011010
c) 00101010
d) 0111110