Question 604770
A good example is when you buy something that costs more money than what you have in your pocket (or bank account). 


Say you have $2 in your pocket and you buy a $5 item. You make a deal with the clerk that you'll pay him/her back the difference. This means that you'll owe 5-2 = 3 dollars.


Since this is an in the form of an IOU or debt, we represent it as a negative number. So this is why we actually write it as 2 - 5 = -3 


The -3 refers to the fact that you owe 3 dollars.