1. Purpose
1-2
Add real numbers.
Subtract real numbers.

2. –4 + (–7) –4+ (–7) = –11 Add or subtract using a number line. + (–7)
Example 1
Add or subtract using a number line.
–4 + (–7)
Start at 0. Move left to –4.
To add –7, move left 7 units.
+ (–7) –4 11 10 9 8 7 6 5 4 3 2 1
–4+ (–7) = –11

3. You Try! –3 + 7 –3 + 7 = 4 Add or subtract using a number line.
Start at 0. Move left to –3.
To add 7, move right 7 units. +7 –3 -3 -2 -1 1 2 3 4 5 6 7 8 9
–3 + 7 = 4

4. You Try! –3 – 7 –3 – 7 = –10 Add or subtract using a number line. 11
Start at 0. Move left to –3.
To subtract 7 move left 7 units. –3 –7 11 10 9 8 7 6 5 4 3 2 1
–3 – 7 = –10

5. The absolute value of a number is the distance from zero on a number line. The absolute value of 5 is written as |5|.
5 units
5 units - 6 - 5 - 4 - 3 - 2 - 1 1 2 3 4 5 6
|–5| = 5
|5| = 5

6. Note: subtracting is the same as adding the opposite.
When adding two #’s with the same sign:
take absolute value
Add
Keep sign of the larger original number
When adding two #’s with the different signs:
take absolute value
Subtract (find the difference)
Keep sign of the larger original number
Note: subtracting is the same as adding the opposite.

7. Add. y + (–2) = (–6) + (–2) (–6) + (–2) –8 Example 2
y + (–2) for y = –6
y + (–2) = (–6) + (–2)
(–6) + (–2) –8

8. Example 3 5 – (–4) 5 − (–4) = 5 + 4 9 Subtract. To subtract –4 add 4.
Find the sum of the absolute
values.

9. You Try!
Subtract.
13 – 21
13 – 21
= 13 + (–21) –8

10. elevation at top of iceberg
Example 4: Oceanography Application
An iceberg extends 75 feet above the sea. The bottom of the iceberg is at an elevation of –247 feet. What is the height of the iceberg?
elevation at top of iceberg 75
elevation at bottom
of iceberg
–247
Minus –
75 – (–247)
75 – (–247) =
= 322
The height of the iceberg is 322 feet.

11. Exit Task Add or subtract using a number line. 2. –5 – (–3) –2
1. –2 + 9 7
Add or subtract.
3. – 19
– (–3.7)
8.2