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b. 1’s complement of 110111.10 is 001000.01        +1                        +1
                          2’s complement of 001000.01 is 001000.10               1   0    0    0   .  0   1
                         Adding 1000.01 and 001000.10, we get    +    0    0     1   0    0    0   .  1   0

                                                                      0    1     0   0    0    0   .  1   1
                                                                     1’s complement of 010000.11 is 101111.00
                         (-101111.01) 2                              2’s complement of 101111.00 is 101111.01
                    16.  Perform the octal addition (1567.2)  + (433.4) 8
                                                  8
                   Ans.      +1   +1  +1
                             1    5    6   7   .  2
                         +        4    3   3   .  4
                             2    2    2   2   .  6
                        (2222.6) 8
                    17.  Perform octal subtraction (3214.6)  - (777.7)  using:
                                                  8
                                                         8
                        a.  Borrow method
                        b. 7’s complement method
                        c.  8’s complement method
                   Ans.  a.
                                  +8     +8      +8        +8
                           3    2       2    1       1   0       4    3  .  6
                                  7       7       7    .   7
                            2     2       1       4    .   7

                            (2214.7) 8
                       b. 7’s complement of 0777.7 is 7000.0        +1
                           Adding 3214.6 and 7000.0, we get               3    2     1    4   .  6
                                                                +         7    0     0    0   .  0
                                                                     1    2    2     1    4   .  6
                                                                                                 1
                           (2214.7)                                       2    2     1    4   .  7
                               8
                       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                            3    6     1
                         7’s complement of 6215 is 1562              +    5     6    3     4
                         (-1562) 8                                        6     2    1     5
                        b. 7’s complement of 2143 is 5634
                         8’s complement of 5634 is 5635                   +1    +1
                         Adding 361 and 5635, we get                            3     6    1
                         7’s complement of 6216 is 1561              +     5    6     3    5
                         8’s complement of 1561 is 1562                    6    2     1    6
                         (-1562) 8




                                                                                              System of Numeration  47
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