Right I am adding the finishing touches to the revision powerpoint I promised you. However, while I was going over sign and magnitude, I came across this.

http://en.wikipedia.org/wiki/Signed_number_representations

“Useful” I hear you say, but there is more to this than meets the eye. There is on that page a method for converting a number to 2’s complement that I haven’t see in quite a while and I thought I might share it with you.

- Starting from the right, find the first ‘1’
- Invert all of the bits to the left of that one

So for 42 to convert it to -42

- 00101010
- 11010110