Subtract using 2's Complements?

Question

a.) 11101 - 110110 =
b.)Multiply 111011 x 110 =
c.)(ABCDF12)hex + (176E0A)hex =
d.)1110111 + 101001 =

Show work please.

Answer 1

http://www.computerhope.com/binhex.htm

Answer 2

subtraction using 2's compliment is a method of performing subtraction by ultimately adding two binary nymbers.

9 - 5 = 4
00001001 - 00000101 = 00000100

Convert into a two's compliment the number you are subtracting (5)

First invert all bits (Compliment) 1's become 0's and 0's become 1's for all bit positions. This is also known as a 1's compliment.

00000101 (5)
11111010 (250)

Next add 1 (1's compliment becomes a 2's compliment)

11111010(250)
00000001(1)
11111011(251) This is the 2's compliment you will add

I am placing an _ as a place holder for the 8 bit overflow
_00001001(9)
_11111011(251)
----------------------- Do the addition bit by bit with the carries.
100000100(260) This is the result of the add (9 bits)

discard the overflow and you are left with 00000100(4)