Page 64 - Computer Science Class 11 Without Functions
P. 64

Ø   Place Value: In decimal number systems, the value of a digit within a number depends on the position of the
              digit.
              For example,
              ○ the rightmost digit is called the one's digit or unit digit (value 100 = one).
              ○ the second digit from the right end is called the tens digit (value 101 = ten).

              ○ the third digit from the right end is called the hundreds digit (value 102 = hundred) and so on.
          Ø   In general, in a positional number system, the leftmost digit is the most significant, and the rightmost digit is
              the least significant digit.

          Ø   The binary number system (base-2) is composed of 2 unique symbols 0 and 1.
          Ø   The octal number system (base-8) is composed of 8 unique symbols: 0. 1,2,3,4,5,6,7.
          Ø   The hexadecimal (her) number system (base-16) is composed of 16 symbols: 0,1,2,3,4,5,6,7,8,9.A.B,C,D,E,F.
              The decimal, binary, octal and hexadecimal systems are positional value systems wherein each component
              digit.
          Ø   Characters are represented in memory by alphanumeric codes. One such code is ASCII (American Standard
              Code Information Interchange) most commonly used encoding scheme used to encode characters in the
              English language.
          Ø   Indian Script Code for Information Interchange (ISCII) — a coding scheme for representing characters in
              various writing systems in India.
          Ø   ISCII is used for encoding the data collected by the election commission. It is also used for encoding the land
              records.

          Ø   UTF-16 is a variable-length encoding scheme that uses 1 byte (8-bits) or 2 bytes (16 bits) to represent the
              characters. It is not compatible with ASCII.

          Ø   UTF-32 is a fixed-length encoding scheme that uses precisely four bytes to represent the characters.





                                               Solved Exercise


        A.  Multiple Choice Questions
           1.  Which of the following number system has a base value of 8?
              a.  Octal                b. Decimal             c. Binary              d. Hexadecimal
           2.  Which of the following is NOT a positional number system?
              a.  Binary               b. Hexadecimal         c. Octal               d. Roman

           3.  Consider the statements given below:
               Statement A: A decimal number system is a positional number system
               Statement B: The place value of a digit is ten times the value of the digit on its right.
              a.  Both statements are correct
              b.  Only statement B is correct.
              c.  Only statement A is correct.
              d.  Both statements are incorrect.
           4.  Consider the decimal number 234.78. What is the place value of the digit 4?
                                            1
                                                                  0
              a.  10                   b. 10                  c. 10                  d. 10 1
                   2

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