Negative Numbers:Addition and Subtraction
Worksheets for adding negative numbers and subtracting negative numbers.
Tricks for Adding and Subtracting Negative Numbers
Adding and subtracting numbers can be confusing at first because the idea of a negative quantity of something can be a strange concept, even to a 6th grader.
Instead, introduce the concept of negative numbers using measurements that might convincingly have negative results. A good example is temperature, where values can fall below zero (This is especially good if Celcius temperatures are understood as zero has a very clear meaning there.) Another good choice would be altitude above or below sea level.
Working with a number line is another great strategy for visualizing how subtracting can create negative integers in a more abstract context.
Keeping Track of the Signs
Part of the challenge with adding and subtracting negative numbers is figuring out what to do with the signs. We learn our subtraction facts and become conditioned to that minus symbol immediately meaning to take the second number away from the right. With negative numbers, this is often wrong.
Here are the rules for adding or subtracting negative numbers:
- Adding a positive number is addition, (e.g., 4 + (+2) = 4 + 2= 6
- Subtracting a negative number is addition, (e.g., 4 - (-2) = 4 + 2 = 6
- Adding a negative number is subtraction, (e.g., 4 + (-2) = 4 - 2 = 2
- Subtracting a positive number is subtraction, (e.g., 4 - (+2) = 4 - 2 = 6
Normally, of course, we don't show the signs on positive numbers, so two of the rules above look just like standard addition and subtraction! The other two rules are the key ones to remember for combining negative numbers... Subtracting a negative value is the same as addition, and adding a negative is the same as subtraction. If students can keep these two new twists in mind, addition and subtraction with negative numbers will be a breeze!