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c. 7’s complement of 0777.7 is 7000.0       +1
                       8’s complement of  7000.0 is 7000.1             3     2    1    4   .  6
                        Adding 3214.6 and 7000.1, we get     +         7     0    0    0   .  1
                       Discarding MSB 1, we get                   1    2     2    1    4   .  7
                       (2214.7) 8

                 18.  Perform octal subtraction (361)  - (2143)  using
                                              8
                                                      8
                      a. 7’s complement method
                      b. 8’s complement method
                Ans.  a.  7’s complement of 2143 is 5634               +1    +1
                       Adding 361 and 5634, we get                 +    5    3     6    1
                                                                                   3
                                                                             6
                                                                                        4
                       7’s complement of 6215 is 1562                   6    2     1    5
                       (-1562) 8
                      b. 7’s complement of 2143 is 5634
                                                                        +1   +1
                       8’s complement of 5634 is 5635
                                                                              3    6     1
                       Adding 361 and 5635, we get                 +    5     6    3     5
                       7’s complement of 6216 is 1561                   6     2    1     6
                       8’s complement of 1561 is 1562
                       (-1562)
                            8
                 19.  Subtract the given hexadecimal numbers (9A78.25)  - (FAD.50)  using
                                                                         6
                                                               16
                      a. Borrow method
                      b. 15’s complement method
                      c. 16’s complement method
                Ans.  a.
                                   +16    +16   +16     +16
                             9   8  A    9  7   6  8    7  .  2  5
                         -          F      A     D    .   5    0
                              8     A      C     A    .  D     5
                           (8ACA.D5) 6

                     b. 15’s complement of  0FAD.50  is F052.AF  +1                         +1
                       Adding 9A78.25 and F052.AF, we get             9    A    7    8   .   2    5
                       (8ACA.D5) 16                         +         F    0    5    2   .   A    F
                                                                 1    8    A    C    A   .   D    4
                                                                                                  1
                                                                      8    A    C    A   .  D     5


                     c. 15’s complement of  0FAD.50  is F052.AF  +1
                       16’s complement of F052.AF is F052.B0          9    A    7    8   .   2    5
                       Adding 9A78.25 and F052.B0, we get   +         F    0    5    2   .   B    0
                       Ignoring MSB 1, we get                    1    8    A    C    A   .  D     5
                        (8ACA.D5) 16








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