Digital Learning

Thursday, May 28, 2020

CBSE-ComputerScience-Class-VII(Solved Exercise-1):

Class-7
Subject: Computer Science
Chapter-1 Number System (Solved Exercise)
                 A.    Name the following:
1.     Rightmost digit of a number                                  __________________
Answer: Least Significant Digit
2.     Leftmost digit of a number                                     __________________
Answer: Most Significant Digit
3.     Digits of binary number system                           __________________  __________________
Answer: 0 and 1
4.     Two examples of hexadecimal number system__________________  _________________
Answer: 5A and 6AB
5.     Base of hexadecimal number system                 __________________
Answer: 16
                B.    Write true or false.
1.     The positional value of each digit increases from right to left.     _____T
2.     The base of binary number system is 8.                                               _____F
3.     Decimal number system has base as 0.                                                 _____F
4.     The instructions given to a computer are converted into decimal language.                                                                                                         _____F
5.     The base of octal number system is 8.                                                   _____T
                 C.     Fill in the blanks:
1.     To convert binary number system to decimal number system, we multiply each digit with its______.
Answer: Positional value i.e. 2
2.     The ________ system consists of 8 digits.
Answer: Octal number system
3.     Binary addition is similar to __________addition.
Answer: Decimal
4.     Any quantity greater than 9 is represented by a contribution of ________ or more digits.
Answer: two
5.     The number system consists of a set of _____________.
Answer: Values
                 D.    Answer the following questions.
1.     Write the steps to perform the following conversions.
a.     Hexadecimal number system to decimal number system.
Answer:
Step 1: Multiply each digit with its positional value, which is in terms of power of 16, starting from the extreme right digit.
Step 2: Increase the power one by one, keeping the base fixed at 16.
Step 3: Add all the products to get the decimal number.
Example: (4D2)16 =(?)10
2*160 =2
D*161 =208 (D=13)
4*162 =1024
=2+208+1024
=1234
(4D2)16=(1234)10
b.     Octal number system to decimal number system.
Answer:
Step 1: Multiply each digit with its positional value, which is in terms of power of 8, starting from the extreme right digit.
Step 2: Increase the power one by one, keeping the base fixed at 8.
Step 3: Add all the products to get the decimal number.
Example: (345)8=(?)10
3*80=5
4*81=32
5*82=192
=5+32+192=229
(345)8=(229)10
c.      Binary number system to decimal number system.
Answer:
Step 1: Multiply each digit with its positional value, which is in terms of powers of 2, starting from the extreme right digit.
Step 2: Increase the power one by one, keeping the base fixed at 2.
Step 3: Add all the products to get the decimal number.
Example:
(1001)2=(?)10
1*20=1
0*21=0
0*22=0
1*23=8
=1+0+0+8=9
(1001)2 =(9)10
d.     Decimal number system to binary number system.
2.     Add 101 and 101.
Answer:
      1 0 1
  + 1 0 1
__________
    1010
__________
3.     Subtract 11 from 101.
Answer:
  1 0 1
    -1 1
___________
     010
___________
4.     Multiply 111 with 011.
Answer:
                        0 0 1
                        *1 1 1
____________
0 0 1
                                0 0 1*
                             0 0 1*
___________________
                                    1 1 1
__________________
5.     Divide 1101 with 111.
Answer:
                                    111)1101(1
                                               111
                                             _________
                                                110 Remainder

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