### Re: Let 'em say we're crazy and get to a MINUS million in bi

Posted:

**16 Jan 2018, 15:47**coleslaw wrote:spotify95 wrote:coleslaw wrote:spotify95 wrote:Binary doesn't use a positive or negative sign - it uses the leading digit as wither 0 (positive) or 1 (negative).

Also remember that Binary only uses 1's or 0's.

You'll need to use 2's Complement to get the binary of negative numbers.

http://en.wikipedia.org/wiki/Two's_complement

To work out 2's compliment, firstly find the binary of the positive number (remember to leave a 0 at the front for the sign)

Then invert all of the digits, and finally add 1 to the result.

Eg: 2 in binary is 010

Invert: 101

2's comp: 110.

Hence -6 in binary:

Positive 6: 0110

Invert: 1001

Add 1: 1010

Why do we need twos complement here? Ones compliment is fine enough for this thread

101100

I've had a look here:

https://www.calvin.edu/academic/rit/web ... gative.htm

And it states that although neither system is more correct than the other, two's compliment is more often used.

Just having the leading character for the sign (0 for positive, 1 for negative) can be a bit confusing with the positive number that is bigger by a power of 2. But we can convert to standard binary if required (making sure the leading 1 is kept).

101010

From what I remember twos complement is better and used more because it retains consistency with arithmetic and operations. Since this thread is just listing the minus numbers in order it's not really needed and we can just do:

Find the binary number = 10111

Put sign in front = 010111

Invert = 101000 = -23

Okay we can do that then

Whichever method you prefer, is what you can use

100101