How to Subtract Integers Without Getting Confused

A whole lot of people run into a problem where they understand how to add integers, but aren’t very confident in their ability to subtract integers. For example, many people will tell you straight-up that 12 + (-4) is 8, that -5 + (-4) is -9, or that 8 + (-14) is -6. These same people will cringe and have lots of anxiety if you ask them what -4 – (-13) is. The reason for this is simple, and we’re going to look at it, then show you how to turn subtraction problems into addition problems so that you don’t have to learn any new skills to be able to subtract integers.

Adding integers is easy because it’s basic in nature. If the signs of the two integers are the same, then you just add them and keep the sign the same. For example, if you have 8 + 4, that’s 12, and -8 + (-4) is -12 along similar lines. If the two integers have different signs, then you subtract them and keep the sign for the larger of the two numbers. For example, -8 + 4 is -4, but 8 + (-4) is 4. This is straight-forward, easy to understand, and easy to master. Most people aren’t taught such a straight-forward method for subtracting integers, but here we’re going to give you one.

The point here is that we’re going to turn a subtraction problem into an addition problem. We’re going to achieve this with one simple step: change the sign of the second number. For example, if we have 5 – 4, which we know to be 1, we can change it into an addition problem by changing the sign of the second number and turning 5 – 4 into 5 + (-4). Note that 5 + (-4) is also 1.

So imagine we have -18 – 5. Change the sign of the second number, and you now have an addition problem: -18 + (-5) = -23. That’s all you’ve got to do to be able to subtract integers quickly and easily.