Discrete Mathematics Multiple Choice Questions on “Logic and Bit Operations”.
1. Which of the following bits is the negation of the bits “010110”?
a) 111001
b) 001001
c) 101001
d) 111111
Answer: c
Clarification: Flip each of the bit to get the negation of the required string.
2. Which of the following option is suitable, if A is “10110110”, B is”11100000” and C is”10100000”?
a) C=A or B
b) C=~A
c) C=~B
d) C=A and B
Answer: d
Clarification: Output of and is 1 when both other inputs are one.
3. How many bits string of length 4 are possible such that they contain 2 ones and 2 zeroes?
a) 4
b) 2
c) 5
d) 6
Answer: d
Clarification: The strings are {0011, 0110, 1001, 1100, 1010 and 0101}.
4. If a bit string contains {0, 1} only, having length 5 has no more than 2 ones in it. Then how many such bit strings are possible?
a) 14
b) 12
c) 15
d) 16
Answer: d
Clarification: The total strings are 1(having no one in it) +5(having 1 one in it) +10 (having 2 ones in it) = 16.
5. If A is “001100” and B is “010101” then what is the value of A (Ex-or) B?
a) 000000
b) 111111
c) 001101
d) 011001
Answer: d
Clarification: In Ex-or if both the inputs are same then output is 0 otherwise 1.
6. The Ex-nor of this string “01010101” with “11111111” is?
a) 10101010
b) 00110100
c) 01010101
d) 10101001
Answer: c
Clarification: In Ex-nor if both the inputs are same then output is 1 otherwise 0.
7. What is the one’s complement of this string “01010100”?
a) 10101010
b) 00110101
c) 10101011
d) 10101001
Answer: c
Clarification: Negate every bit in one’s complement.
8. What is the 2’s complement of this string “01010100”?
a) 10101010
b) 00110100
c) 10101100
d) 10101001
Answer: c
Clarification: In two’s complement negate every bit from left until the first one from right is encountered.
9. If in a bits string of {0,1}, of length 4, such that no two ones are together. Then the total number of such possible strings are?
a) 1
b) 5
c) 7
d) 4
Answer: c
Clarification: Strings can be {1001, 1010, 0101, 1000, 0100, 0010, 0001}.
10. Let A: “010101”, B=?, If { A (Ex-or) B } is a resultant string of all ones then which of the following statement regarding B is correct?
a) B is negation of A
b) B is 101010
c) {A (and) B} is a resultant string having all zeroes
d) All of the mentioned
Answer: d
Clarification: In Ex-or both if both the inputs are the same then output is 0 otherwise 1.