Rules
When you add two numbers with the same sign, you...
Add the absolute values and keep the sign
-5 + -12 =
-17
12 - (-12) =
24
(−0.5) + 0.3 =
−0.2
17.9 − (−19.4) =
37.3
When subtracting, what happens to the first number?
It stays the same!
-14 + 16 =
2
-14 - 5 =
-19
13.7 + 3.2 =
16.9
15.5 − 15.5 =
0
When subtracting, what do you FIRST change?
180 + -20 =
160
-20 - (-8) =
-12
(−4.79) + (−0.4) =
-5.19
2.2 − 7.3 =
−5.1
When subtracting, what do you do to the second number?
-94 + -6 =
-100
-71 - 80 =
- 151
(−7.1) + 3.63 =
−3.47
(−3.9) − 8.9 =
−12.8
When adding two numbers with different signs, you...
Subtract the absolute values and keep the sign of the larger number.
-8420 + 680 =
-7560
-190 - (-17) =
-173
(−4.3) + 14.5 =
10.2
(−18.278) − (−6.8) =
−11.478