# Lesson 1.5 Adding Integers - PowerPoint PPT Presentation

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Lesson 1.5 Adding Integers. Vocabulary. Absolute Value - The distance a number is from zero. *Always positive Example: |-9| = 9 |9| = 9 Opposites - Have the same absolute value but different signs. 6 and -6 are opposites -30 and 30 are opposites. Adding Integers Rule #1.

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### Vocabulary

Absolute Value- The distance a number is from zero. *Always positive

Example: |-9| = 9 |9| = 9

Opposites- Have the same absolute value but different signs.

6 and -6 are opposites

-30 and 30 are opposites

If the numbers have the same sign, find the sum of the absolute values and keep the common sign.

Examples: 5 + 6 = |5| + |6| = 11

- 4 + (-3) = - 7 because 4 + 3 = 7 and both signs are negative so the final answer is negative.

-20 + (-10) = -30 because 20 + 10 = 30 and both signs are negative so the final answer is negative.

### Practice

1.) -7 + (-8)

2.) -15 + (-2)

3.) -36 + (-5)

If the signs are different, find the difference of the absolute values and keep the sign of the bigger number.

Examples: -10 + 4 = -6 because 10 – 4 = 6

and 10 is bigger than 4 and 10 was negative.

7 + (-9) = -2 because 9 – 7 = 2

and 9 is bigger than 7 and 9 was negative.

-11 + 20 = 9 because 20 – 11 = 9

and 20 is bigger than 11 and 20 was positive

### Practice

1.) – 25 + 6

2.) 30 + (-9)

3.) -22 + 55

The sum of a number and its opposite is 0.

Examples: - 9 + 9 = 0

8 + (-8) = 0

-25 + 25 = 0

### Subtracting Rule

To subtract integers, add the opposite of the second number. Then follow one of the three adding rules.

Examples:

-12 – 2 = -14 because -12 + (-2) follows adding rule #1. 12 + 2 = 14 and both signs are negative so the final answer is negative.

-8 – (-10) = 2 because -8 +10 follows adding rule #2.

10 – 8 = 2 and 10 is bigger than 8 and 10 is positive.

1.) 4 – 10

2.) 7 – (-5)

3.) – 2 – (-9)

4.) 2 – 6

5.) 3 – (-8)

6.) -7 - 4