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

The last rule you need to know is how to subtract a negative number. For example, suppose you want to calculate math . Here’s the up and down rule:

Remember Subtracting a negative number is the same as adding a positive number — go up on the number line.

This rule tells you that math is the same as math , so start at math :

Tip When subtracting negative numbers, you can think of the two negative signs canceling each other out to create a positive.

Example Q. Use the number line to add math .

A. 2. On the number line, math means math which brings you to 2:

An illustration of negative numbers on the number line.

Q. Use the number line to add math .

A. 4. On the number line, math means start at 6, down 2, which brings you to 4:

Q. Use the number line to add math .

A. −7. On the number line, math means math which brings you to −7:

Q. math

A. 16. Switch around the two numbers with the signs attached:

Now you can drop the plus sign and use the negative sign for subtraction:

Q. Use the number line to subtract math

A. −5. On the number line, math means start at −1, down 4, which brings you to −5:

Q. Use the number line to subtract math .

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

An illustration of negative numbers on the number line.

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

(a) math

(b) math

(c) math

(d) math

(e) math

(f) math

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

(a) math

(b) math

(c) math

(d) math

(e) math

(f) math

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

(a) math

(b) math

(c) math

(d) math

(e) Скачать книгу