Page 44 - ComputerScience_Class_11

Let’s Revisit

♦ Popular number systems are decimal, binary, octal and hexadecimal.
♦ The base of a decimal number system is 10 and digits are 0 to 9.
♦ The base of a binary number system is 2 and digits are 0 and 1.

♦ The base of an octal number system is 8 and digits are 0 to 7.
♦ The base of a hexadecimal number system is 16 and digits are 0 to 9 and A(10), B(11), C(12), D(13), E(14) and F(15).
♦ Calculations like addition, subtraction, multiplication and division can be performed on these numbers.
♦ 1’s complement of a binary number is obtained by replacing 1 with 0 and 0 with 1.

♦ 2’s complement is calculated by adding 1 to 1’s complement.
♦ 7’s complement of an octal number is obtained by subtracting each digit from 7.
♦ 8’s complement is calculated by adding 1 to 7’s complement.
♦ 15’s complement of a number is obtained by subtracting each digit from 15.
♦ 16’s complement is calculated by adding 1 to 15’s complement.

MIND DRILL

Solved Questions

A. Tick ( ) the correct option.

1. For a number system of base ‘b’, the possible number of digits are ………………… .
a. 0 to b b. 1 to b
c. 1 to b-1 d. 0 to b-1
2. Which of the following is not an example of a binary number?
a. 100110 b. 200.200
c. 1000.0110 d. 111.1
3. To express an octal number into its binary equivalent, each octal digit is expressed into ………………… .
a. 16 bits form b. 4 bits form
c. 3 bits form d. 8 bits form

4. Which of the following will occupy more memory space?
a. (234) b. (789)
10
8
c. (ABC.D) d. (10011) 2
16
5. In a binary number system, the leftmost bit contains maximum weight and is called ………………… .
a. MSB b. LSB
c. Both a and b d. None of these

6. Which of the following is not a positional number system?
a. Roman Number System b. Octal Number System
c. Binary Number System d. Hexadecimal Number System
7. 7’s complement of Octal number 523 is ………………… .
a. 777 b. 365
c. 254 d. 255

42 Touchpad Computer Science (Ver. 3.0)-XI