Add +25 to -15 by using 2's complement ?

Ans. Firstly convert the numbers 25 and 15 in its 8-bit binary equivalent and determine the 2's complement of 15, after that add +25 to -15.
          15= 0 0 0 0 1 1 1 1 (8-bit binary equivalent of 15)

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

 = -15 =  1 1 1 1 0 0 0 1 (2's complement of 15)
        +25 = 0 0 0 1 1 0 0 1 (8-bit binary equivalent of 25)
      ------------------------------ Addition of -15 to +25
        +10 = 0 0 0 0 1 0 1 0
     ------------------------------- Thus -15 to +25 = (10)₁₀ = (1010)₂.