1. (computer – Online Book)
1.3 Adding Integers
(computer – Online Book)

2. opposites 2 and –2 The corresponding number located the
same distance from zero, but on the
opposite side of the number line
For example
2 and –2
2 units
2 units

3. NOTE: Another name for opposite is Additive Inverse.
opposites
Also…
–6 and 6
6 units
6 units
NOTE: Another name for opposite is Additive Inverse.

4. Additive Inverse Property
The sum of an integer and
its opposite is always 0.
a + (–a) = 0
7 + (–7) = 0

5. Rule #1 for Adding Integers
If the signs of two integers are the same (both positive or both negative)
Add the integers.
Keep the original sign of the integers.
For Example…
–2 + (–8) – 10
Use “Counters” & check with “Number line”.

6. Simplify
–3 + (–5) – 8
Use “Counters” & check with “Number line”.

7. Simplify
–15 + (–13) – 28
6 + 13 19
Try it!

8. Rule #2 for Adding Integers
If the signs of two integers are different
(one positive and one negative)
Subtract the numbers.
(Ignore the signs for now.)
Keep the sign of the integer with
the greatest absolute value.
(farthest number from zero)
For Example…
2 + (–8) – 6
Use “Counters” & check with “Number line”.

9. Simplify
–6 + 9 3
Use “Counters” & check with “Number line”.

10. Simplify – – 2
3 + (–24) – 21
Try it!

11. Simplify
–4 + (–17) – 21
Try it!

12. Simplify
–15 + │–13│
–15 + 13 – 2
Try it!

13. Simplify
│–63│ + │–33│ 63
+ 33 96
Try it!

14. Simplify
│–11 + (–31)│
│–42│ 42
Try it!

15. Simplify
–9 + (–6) + 4
–15
+ 4 – 11
Try it!

16. Simplify
– (–8)
–10
+ 5 – 5
Try it!

17. Simplify
9 + (–7) + 2 11
+ (–7) 4
Try it!

18. │a│ + │b│ + a for a = –5 and b = –1
Evaluate
│a│ + │b│ + a for a = –5 and b = –1
│–5│ + │–1│ + (–5)
(–5) 1
Try it!

19. Sample Application Problem
(Please refer to Textbook Example 3 on p.11)

20. Homework
p all,12-44 even, 53
(MC #4,5,6)