The digital world runs on binary. But while numbers made up of ones and zeroes is easy enough to get your head round, what happens when you need to express a negative number in digital form?
In fact, it's not too dissimilar to the way we put a minus sign at the left-most side of a number: you simply place a sign bit at the left, which takes a value of 0 or 1 if the number is positive or negative. But, as Professor Brailsford explains in this video, it doesn't always go to plan -- and it can be embarrassing, or even dangerous, when it goes wrong. [Computerphile]