Question

binary,


So I have this: http://screencast.com/t/qg7WOO6c

How do I know that the first and the second line are negative if they dont tell me their values next to the lines?

Answer 1

coz, the MSB (most significant bit) is a "1"

Answer 2

they should tell you that the math is for signed binary numbers somewhere in the question

Answer 3

how about their values after the sign?

Answer 4

in signed binary numbers, taking a 2's compliment make the number -ve

so, +3= "011"
and -3="101"
you add and subtract the same way as any binary number.

lets do +3 + (-3)
0 1 1
1 0 1
-------
1 0 0 0 = (0)

the additional carry of "1" is rejected.

Answer 5

@Christos

This reference from Dr. Math may help.
This is my first time seeing complements of binary numbers.

http://mathforum.org/library/drmath/view/55924.html

Answer 6

ty both guys