The difference between two numbers can be positive, negative, or zero. Positive differences occur when the first number is greater than the second number, such as in the example used above: 117-28=89. Negative differences happen when the first number is less than the second number. If we reversed the numbers in our example, we would have 28-117=-89. If the two numbers are equal to each other, then their difference is zero: 117-117=0.