6th Grade Math Textbook, Fundamentals

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1-4

Model Alyssa’s

old score, 9.

There are five

1 tiles left.

 9  5

Update your skills. See page 409 VI.

Subtract Integers

Objective To model subtraction of integers• To subtract integers with like and unlike signs

Alyssa and Heather are playing a board game they
made up. A player who lands on blue adds  4
to her score. A player who lands on white subtracts  4
from her score. Alyssa lands on white. If her score
was 9, what is her new score?

You can use tiles or a number line to model

subtraction of integers with like signs.

To find Alyssa’s new score, subtract:  9 (4)

Method 1 Use Tiles

Method 2 Use a Number Line

• Start at 0, move left to 9.


• Move right to add 4.

So Alyssa’s new score is 5.

To subtract 4,

remove four 1 tiles.

(4)

 9  8  7  6  5  4  3  2  1 01

4

 9

Think

(4) 4, so subtracting 4 is the

same as adding 4.

You can use opposites to subtract integers

with like signs. Two integers that are opposites

are called of each other. The

sum of an integer and its additive inverse is 0.

additive inverses

Key Concept

Subtracting Integers

To subtract an integer, add its opposite,

or additive inverse.

aba(b)

Subtract: 12  15

12 (15)

12 (15)

 3

So 12  15 3.

| 15 || 12 |

The result is negative.

Add the opposite of the

number being subtracted.

Subtract:  7 (12)

 7 (12)

 7  12

5

So  7 (12) 5.

| 12 || 7 |

The result is positive.

Add the opposite of the

number being subtracted.

Remember:  1