Solution of chapter-2(Number system) class-7 Sub- ICT World | Computer

 

A. Tick (✓) the correct option.

1. Express (10110)₂   into its decimal equivalent.

(b) 22

2. Express (12)₁₀  into its binary equivalent.

_{(a) 01100   (there is no correct option in the book)}

_{3. Express}  (10)8 into its decimal equivalent.

(d) 8

4. Express  (12)₁₀    into its octal equivalent.

(b) 14

5. Express (30)₁₀ into its hexadecimal equivalent. 

(c) 1E

B. Write (T) for true and (F) for false statements.

1. The decimal number system has only two numbers, 0 and 1.     [F]

2. The octal number system consists of 8 digits 0,1,2,3,4,5,6,7      [T]

3. The binary number system consists of digits 0-9.                        [F]

4. Hexadecimal number system consists of 16 symbols 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E

    and  F.      [T]

5. 120011 is an example of binary number.      [F]

C. Answer the following questions.

1. Why do you need a binary system ?

Ans. The Binary number system has only two numbers, 0 and 1. It is the most fundamental numbering system in digital computers.

2. Why is binary system used in computer? 

Ans. The reason is that the computer is an electronic machine and  understands two states ON (represented by 1) and OFF (represented by 0). Therefore, the instructions given to a computer is converted to binary form because a computer understands only the binary language. 

3. Briefly describe the decimal number system.

Ans. The Decimal number system consists of digits 0-9. These 10 digits can be used in any combination to form any number. Examples of decimal numbers are : 6043, 12687, 561.

4. Differentiate between decimal and octal number system.

Ans. Decimal Number System:-  The Decimal number system consists of digits 0-9. These 10 digits can be used in any combination to form any number. The base of decimal number system is 10 because the total digits in this number system is 10.

Octal Number System:- The Octal number system is another type of number system has the base 8. It is also called base 8 number system. This number system consists of 8 digits, 0,1,2,3,4,5,6, and 7.

5. List the number representation in the hexadecimal number system.

Ans. Hexadecimal number system uses the base 16 system. This number system consists of 16 symbols-0,1,2,3,4,5,6,7,8,9,A,B,C,D,E and F.

Here the letters represent the following number:

A - 10, B-11, C-12, D-13, E-14, F-15.