Blooming Buds Co- Ed. School, Sambhal
Session- (2021-22)
Teacher Name:
Subject:
Class- 7th
Chapter Name:-
Notes
Mr. Ramesh
Computer
Chapter - 2
Number System
Extra Important QuestionAnswer the following questions.
Q1. What do you means by number system?
Ans- A system for representing (that is expressing or writing) numbers
of a certain type is called number system. The types are:
 Decimal number system
 Binary number system
 Octal number system
 Hexadecimal number system
Q2. What is octal number system? How to convert octal number
into decimal number.
Ans- Octal Number System
The octal number system consists of eight digits from 0 to 7. The
base of the octal number system is 8
Example- In the octal system each place is a power of eight.
The octal number system (273)8
 Conversion of a octal number into a decimal number
Example
(273)8= (( 2 x 82)
+ (7 x81) + (3 x 80))10
(273)8= (2x64
+ 7x8
+ 3x1)10
(273)8= (128
+ 56
+ 3)10
(273)8= (187)10
Convert the following binary numbers into decimal numbers.
Q3.
a. 11001
Starting from last digit
= (1x20 ) + (0x21 ) + (0x22 ) + (1x23 ) + (1x24 )
= 1+0+0+8+16
=25
Q4.
b. 111001
Starting from last digit
=(1x20 )+(0x21 )+(0x22 )+(1x23 )+(1x24 )+(1x25 )
= 1+0+0+8+16+32
=57
Question 5:
Convert (39286)10 to octal form.
Answer:
(39286)10 = (114566)8
Question 6:
Do as directed :
(a) Convert the Decimal number 781 to its Binary equivalent.
Answer:
Do as directed :
Question 7:
Covert the Hexadecimal number 3BC into its Binary equivalent.
Answer:
Do as directed
Q8. Covert the Octal number 576 to Decimal.
Answer-
Q9. Convert the Hexadecimal number A5C1 to Decimal,
Answer:
Q10. Name the most popular number system.
Ans- Decimal number system.