Basic Math & Pre-Algebra All-in-One For Dummies (+ Chapter Quizzes Online). Mark Zegarelli

      Q. Use the number line to subtract .

      A. −2. The expression means start at (because the two negative signs cancel each other out), which brings you to :

      5 Use the number line to solve the following addition problems:

      (a)

      (b)

      (c)

      (d)

      (e)

      (f)

      6 Solve the following addition problems without using the number line:

      (a)

      (b)

      (c)

      (d)

      (e)

      (f)

      7 Use the number line to solve the following subtraction problems:

      (a)

      (b)

      (c)

      (d)

      (e)

      (f)

      8 Solve the following subtraction problems without using the number line:

      (a)

      (b)

      (c)

      (d)

      (e)

      (f)

Knowing Signs of the Times (and Division) for Negative Numbers

      Multiplication and division with negative numbers is virtually the same as with positive numbers. The presence of one or more negative 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,

      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 of 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.

      

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