Add -20 to +26 by using 2's complement ?

Ans. Firstly convert the both numbers 20 and 26 in its 8-bit binary equivalent and determine the 2's complement of 20, after that add -20 to +26, that is,
               20 =  0 0 0 1 0 1 0 0 (that is 8-bit binary equivalent of 20)

              = 1 1 1 0 1 0 1  1  (1's complement)
                                         +1
           -------------------------------

        = -20 = 1 1 1 0 1 1 0 0 (i.e. 2's complement of 20)
               +26 = 0 0 0 1 1 0 1 0 (8-bit binary equivalent of 26)
           ----------------------------- Addition of -20 to +26
              = +6 = 0 0 0 0 0 1 1 0
           ----------------------------- Thus -20 to +26 = (6)₁₀ = (0110)₂.