1. Adding & Subtracting Integers
LESSON 1-5

2. ADDING INTEGERS ( +3) + (+2) = +5 ○ ○ ○ + ○ ○ = ○ ○ ○ ○ ○
○ ○ ○ + ○ ○ = ○ ○ ○ ○ ○
“temperature is +3 and add +2 (hot) degrees, temperature gets hotter”
When a number is positive, you do not have to use the (+) sign.
(+3) + (+2) = 5

3. ADDING TWO NEGATIVE NUMBERS
(- 2) + (- 1) = - 3
● ● + ● = ● ● ●
“temperature is -2 and add -1 (cold) degrees, temperature gets colder”

4. ○ + ● cancel out to get nothing
Adding +1 and -1
(+1) + (-1) = 0
○ + ● cancel out to get nothing

5. ADDING POSITIVE AND NEGATIVE INTEGERS
(+3) + (-4) = -1
○ ○ ○ + ● ● ● ● = ●
(+3) + (-1) = 2
○ ○ ○ + ● = ○ ○ ○

6. ADDING POSITIVE AND NEGATIVE INTEGERS
(-5) + (+3) = -2
● ● ● ● ● + ○ ○ ○ = ● ●
(-3) + (+4) = 1
● ● ● + ○ ○ ○ ○ = ○

7. ADDING POSITIVE AND NEGATIVE INTEGERS
Use temperature to see if this makes sense.
OR, you may notice the following “rule”:
“When adding positive and negative integers, keep the sign of the larger number and subtract.”

8. SUBTRACTING INTEGERS (+3) - (+2) = 1 ○ ○ ○
“temperature is +3 and take away 2 hot degrees, so temperature gets colder”

9. SUBTRACTING INTEGERS (- 3) - (- 1) = - 2 ● ● ●
“temperature is -3 and take away 1 (cold) degrees, temperature gets warmer”

10. SUBTRACTING INTEGERS (+3) - (+4) = ○ ○ ○
Not enough to take away! So add a “zero”.
○ ○ ○ ○ ●
Take away +4 ○ ○ ○ ○ ●
Left with -1
So (+3) - (+4) = -1

11. SUBTRACTING INTEGERS (-4) - (+1) = -5 ● ● ● ● ● ○ (-2) - (+3) = -5
(-4) - (+1) = -5
● ● ● ● ● ○
(-2) - (+3) = -5
● ● ● ● ● ○ ○ ○

12. SUBTRACTING INTEGERS (+3) - (-2) = 5 ○ ○ ○ ○ ○ ● ● (+1) - (-3) = 4
(+3) - (-2) = 5
○ ○ ○ ○ ○ ● ●
(+1) - (-3) = 4
○ ○ ○ ○ ●●●

13. SUBTRACTING INTEGERS Use temperature to see if this makes sense.
OR, you may notice the following “rule”:
“When subtracting positive and negative integers, add the opposite!”

14. YOU TRY ADD SUBTRACT 1) (+6) + (-2) 1) (7) – (2) 2) (+7) + 3
2) (+8) – (-2)
3) (-5) + (+2)
3) (-9) – (+3)
4) (-3) + (-8)
4) (-2) – (-5)

15. ADD
SUBTRACT
1) (+6) + (-2) = 4
1) (7) – (2) = 5
2) (+7) + 3 = 10
2) (+8) – (-2)
= (+8) + (+2)
= 10
3) (-5) + (+2) = -3
3) (-9) – (+3)
= (-9) + (-3)
= - 12
4) (-3) + (-8) = -11
4) (-2) – (-5)
= (-2) + (+5)
= 3