# Computer Fundamentals MCQ focuses on “The Decimal Number System”.

1. The value of base in a decimal number system is __

a) 8
b) 2
c) 10
d) 16

Explanation: A decimal number system consists of 10 digits from 0 to 9. The definition of base describes it as a quantity to represent the number of digits present in that particular number system. Therefore, here, the base is 10.

2. Convert : (110)2 = ( __ )10 .

a) 4
b) 5
c) 6
d) 9

Explanation: The base 2 represents that the number is binary ,whereas, the base 10 represents that it is to be converted to the decimal format. Conversion: 22 * 1 + 21 * 1 + 20 *0 = 6.

3. The 2’s complement of 15 is __

a) 0000
b) 0001
c) 0010
d) 0100

Explanation: 2’s complement is obtained by adding 1 to the 1’s complement of the number. Here, Binary of 15 = 1111 1’s complement of 15= 0000 2’s complement of 15= 0000+1=0001

4. Another name for base is __

a) root
c) entity
d) median

Explanation: Another name for base is radix. Base refers to the number of digits that a particular number system consists of. The base of decimal number system is 10 , binary is 2 and so on.

5. The decimal equivalent of (0.101)2 will be __

a) 0.5
b) 0.625
c) 0.25
d) 0.875

Explanation: Since the base is 2 , it could be easily guessed that the number is binary. Conversion: 2-1 * 1 + 2-2 * 0 + 2-3 * 1 = 0.625.

6. The signed magnitude for -3 will be _

a) 00000011
b) 10000011
c) 11111101
d) 11111100

Explanation: Signed Magnitude of a number is a representation to determine if the number is positive or negative. If the MSB of a number is 0 , the number is positive , else if it is 1 the number is negative. Here, +3 = 00000011 -3= 100000011.

7. A number with both integer and a fractional part has digits raised to both positive and negative powers of 2 in a decimal number system.

a) True
b) False

Explanation: In a decimal number system, a number with both integer and a fractional part has digits raised to both positive and negative powers of 10 and not 2. e.g. 22.34 = 2 * 101 + 2 * 100 + 3 * 10-1 + 4 * 10-2.

8. The hexadecimal representation of 14 is ___

a) A
b) F
c) D
d) E

Explanation: The hexadecimal representations are as follows: 10 : A 11 : B 12 : C 13 : D 14 : E 15 : F.

9. Which of the following is not a decimal number?

a) 114
b) 43.47
c) 99.9A
d) 1010

Explanation: All the numbers except 99.9A are decimal numbers. This number has a hexadecimal component A in it therefore, it is not a valid decimal number. The decimal equivalent of A is 10.

10. Select the incorrect option :

a) (101)10 = (1100101)2
b) G is valid in hexadecimal system.
c) C represents 12
d) The base of a decimal number system is 10