Digital Electronics/Circuits Multiple Choice Questions on “Binary Coded Decimal(BCD.”.
1. Binary coded decimal is a combination of __________
A. Two binary digits
B. Three binary digits
C. Four binary digits
D. Five binary digits
Answer: C
Clarification: Binary coded decimal is a combination of 4 binary digits. For example-8421.
2. The decimal number 10 is represented in its BCD form as __________
A. 10100000
B. 01010111
C. 00010000
D. 00101011
Answer: C
Clarification: The decimal number 10 is represented in its BCD form as 0001 0000, in accordance to 8421 for each of the two digits.
3. Add the two BCD numbers: 1001 + 0100 = ?
A. 10101111
B. 01010000
C. 00010011
D. 00101011
Answer: C
Clarification: Firstly, Add the 1001 and 0100. We get 1101 as output but it’s not in BCD form. So, we add 0110 (i.e. 6) with 1101. As a result we get 10011 and it’s BCD form is 0001 0011.
4. Carry out BCD subtraction for (68) – (61) using 10’s complement method.
A. 00000111
B. 01110000
C. 100000111
D. 011111000
Answer: A
Clarification: First the two numbers are converted into their respective BCD form using 8421 sequence. Then binary subtraction is carried out.
5. Code is a symbolic representation of __________ information.
A. Continuous
B. Discrete
C. Analog
D. Both continuous and discrete
Answer: B
Clarification: Code is a symbolic representation of discrete information, which may be present in the form of numbers, letters or physical quantities. Mostly, it is represented using a particular number system like decimal or binary and such like.
6. When numbers, letters or words are represented by a special group of symbols, this process is called __________
A. Decoding
B. Encoding
C. Digitizing
D. Inverting
Answer: B
Clarification: When numbers, letters or words are represented by a special group of symbols, this process is called encoding. Encoding in the sense of fetching the codes or words in a computer. It is done to secure the transmission of information.
7. A three digit decimal number requires ________ for representation in the conventional BCD format.
A. 3 bits
B. 6 bits
C. 12 bits
D. 24 bits
Answer: C
Clarification: The number of bits needed to represent a given decimal number is always greater than the number of bits required for a straight binary encoding of the same. Hence, a three digit decimal number requires 12 bits for representation in BCD format.
8. How many bits would be required to encode decimal numbers 0 to 9999 in straight binary codes?
A. 12
B. 14
C. 16
D. 18
Answer: B
Clarification: Total number of decimals to be represented = 10000 = 104 = 2n (where n is the number of bits requireD. = 213.29. Therefore, the number of bits required for straight binary encoding = 14.
9. The excess-3 code for 597 is given by __________
A. 100011001010
B. 100010100111
C. 010110010111
D. 010110101101
Answer: A
Clarification: The addition of ‘3’ to each digit yields the three new digits ‘8’, ’12’ and ’10’. Hence, the corresponding four-bit binary equivalents are 100011001010, in accordance to 8421 format.
10. The decimal equivalent of the excess-3 number 110010100011.01110101 is _____________
A. 970.42
B. 1253.75
C. 861.75
D. 1132.87
Answer: A
Clarification: The conversion of binary numbers into digits ‘1100’, ‘1010’, ‘0011’, ‘0111’ and ‘0101’ gives ’12’, ‘5’, ‘3’, ‘7’ and ‘5’ respectively. Hence, the decimal number is 970.42.