Key Terms
The set of numbers less than zero.
negative numbers
The rule for adding two numbers with the same sign.
add the numbers and keep the sign
-20 + (-14) =
-34
-7 - 12 =
-19
rational numbers
The distance between a number and zero.
Absolute Value
The rule for adding two numbers with different signs.
subtract the numbers and take the sign of the number with the larger absolute value.
19 + (-7) =
12
2.7 - 3 =
-0.3
12 + (−5) + 3
10
Two different numbers that have the same absolute value.
opposite numbers
Having a greater absolute value.
the distance from zero is farther
-15.7 + 9.2 =
-6.5
7.6 - (-10) =
17.6
1.39 - 9.23 + (-1.20)
1.39 + (-9.23) + (-1.20)
-7.84 + (-1.20)
-9.04
The set of whole numbers and their opposites.
integers
The rule for subtracting integers or rational numbers.
Rewrite the equation using addition and then add the opposite.
-1/4 + 6/8
1/2
83.36 - (-46.50) =
129.86
Yesterday Kirk borrowed $13.50 from his friend. Today he borrowed $8.50 more. He plans to pay his friend back $15 tomorrow. What will Kirk’s balance be?
-$13.50 + (-$8.50) + $15 = -$7
Kirk's balance will be -$7
A pair of numbers whose sum is zero
zero pair
Rewrite the problem and the get the answer:
-11 - (-5) =
-11 + 5 = -6
-5/9 + -7/6
-1 13/18
3/8 - 1/3
1/24
Tien started hiking from 32.4 meters below sea level. She climbed 61.5 meters in elevation during the hike. What number represents the highest elevation she reached?
-32.4m + 61.5m = 29.1m
The highest elevation Tien reached was 29.1m.