From the course: Learning Algebra: Pre-Algebra

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Identifying the rule for subtracting integers

Identifying the rule for subtracting integers

From the course: Learning Algebra: Pre-Algebra

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Identifying the rule for subtracting integers

- I hope you've memorized those addition rules, because we're now going to use them to help us to subtract integers. Our first example, we're going to evaluate the problem negative two minus four. We're going to use a number line to help us to evaluate this problem. For this problem, we're going to start on negative two on the number line. We're subtracting four. When we subtract numbers, we move to the left on the number line. So, I'm going to move to the left four spaces, one, two, three, four. I end up on negative six. That means that negative two minus four is equal to negative six. For our next problem, we're going to evaluate negative two minus four, but this time we're going to use integer chips. We're going to start with two red integer chips. This indicates negative two. We need to take away four positive integer chips, however I don't have four yellow integer chips to take away. This is where the zero pairs come into play. If I add four positive integer chips, I need to add…

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