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20.  Subtract (1B7)  - (8D27)  using
                                   16
                                           16
                        a. 15’s complement method
                        b. 16’s complement method
                   Ans.  a. 15’s complement of 8D27 is 72D8             +1
                         Adding 1B7 and 72D8, we get                     1    B     7
                          15’s complement of 748F is 8B70     +    7     2    D     8
                         (-8B70) 16                                7     4    8     F

                        b. 15’s complement of 8D27 is 72D8              +1    +1
                          16’s complement of 72D8 is 72D9                1    B     7
                         Adding 1B7 and 72D9, we get 7490     +    7     2    D     9
                          15’s complement of 7490 is 8B6F          7     4     9    0
                          16’s complement of 8B6F is 8B70
                         (-8B70) 16


                      Unsolved Questions



                 A.  Tick ( ) the correct option:
                     1.  Which of these is the base of an octal number system?
                       a.  2                                           b.  8
                       c.  16                                          d.  10
                     2.  The binary equivalent of the decimal number 9 is ………………… .
                       a.  1000                                        b.  1010
                       c.  1001                                        d.  1011
                     3.  Which of the following is not an octal number?
                       a.  827                                         b.  567
                       c.  777                                         d.  245.27
                     4.  To express a hexadecimal number to its binary equivalent, each hexadecimal digit is expressed into ………………… .
                       a.  2 bits form                                 b.  3 bits form
                       c.  4 bits form                                 d.  15 bits form

                     5.  The octal equivalent of decimal number 10 is ………………… .
                       a.  1010                                        b.  A
                       c.  0010                                        d.  12
                     6.  Adding binary digits 1+1+1 will result in ………………….
                       a.  Sum 1, Carry 0                              b.  Sum 0,  Carry 1
                       c.  Sum 3, Carry 0                              d.  Sum 1,  Carry 1
                     7.  Adding octal digits 6+7 will result in ………………… .
                       a.  Sum 13, Carry 0                              b.  Sum 5, Carry 1
                       c.  Sum 1, Carry 5                              d.  Sum 7, Carry 1

                     8.  15’s complement of  hexadecimal number AB51 is ………………… .
                       a.  54AE                                        b.  55AF
                       c.  65BF                                        d.  65BE
                     9.  In decimal to binary conversion, the first remainder is called ………………… .
                       a.  MSB                                         b.  FSB
                       c.  LSB                                         d.  RSB
                    10.  Subtracting 1-0 in binary number system gives ………………… .
                       a.  Result 1, borrow 0                          b.  Result -1, borrow 1
                       c.  Result 1, borrow 1                          d.  Result 0, borrow 1




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                                                                                                            Numbers     43
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