Basic Math & Pre-Algebra For Dummies
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Multiplication and division with negative numbers is virtually the same as with positive numbers. The presence of one or more minus signs (–) doesn't change the numerical part of the answer. The only question is whether the sign is positive or negative.

Just remember that when you multiply or divide two numbers,

  • If the numbers have the same sign, the result is always positive.

  • If the numbers have opposite signs, the result is always negative.

For example,


As you can see, the numerical portion of the answer is always 6. The only question is whether the complete answer is 6 or –6. That's where the rule of same or opposite signs comes in.

Another way of thinking about this rule is that the two negatives cancel each other out to make a positive.

Similarly, look at these four division equations:


In this case, the numerical portion of the answer is always 5. When the signs are the same, the result is positive, and when the signs are different, the result is negative.

About This Article

This article is from the book:

About the book author:

Mark Zegarelli is a professional writer with degrees in both English and Math from Rutgers University. He has earned his living for many years writing vast quantities of logic puzzles, a hefty chunk of software documentation, and the occasional book or film review. Along the way, he’s also paid a few bills doing housecleaning, decorative painting, and (for ten hours) retail sales. He likes writing best, though.

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