Vocabulary
What is the answer to an addition problem called?
sum
0.1 + 0.73
0.83
7.8 - 4.9
2.9
Round the following number to the nearest tenth.
74.362
74.4
Joanne bought three books that cost $3.95, $4.99, and $6.05. How much did she spend in all?
Joanne spent $14.99.
What is the answer to a subtraction problem called?
difference
1.22 + 0.34
1.56
8.04 - 0.3
7.74
Round the following number to the nearest hundredth.
222.222
222.22
James bought school supplies. He bought a notebook for $2.45, a package of mechanical pencils for $3.79, and an eraser for $1.55. How much did he spend in all?
James spent $7.79.
What is rounding or estimating a number to an easier to use value?
For example:
26.23 + 13.5
25 + 15
Compatible Numbers
1.03 + 0.36
1.39
65.9 - 28.38
37.52
Round the following number to the underlined digit.
84.59
85
A bottle of perfume holds 0.55 fluid ounce. A bottle of cologne holds 0.2 fluid ounce. How many more ounces does the bottle of perfume hold?
The bottle of perfume holds 0.35 fluid ounce more.
What property of addition is being shown?
25.3 + 56.9 = 56.9 + 25.3
Associative Property of Addition
4.98 + 3.02
8
34.49 - 12.610
21.88
Round the following number to the underlined digit.
9.969
10
Patrick has a 600-meter skein of yarn. He used 248.9 meters of yarn to make a hat. Does he have enough yarn left to make a scarf that uses 354.03 meters of yarn? Explain.
No, 248.9 + 354.03 = 602.93 which is greater than 600.
What property of addition is being shown?
477.75 + (76.89 + 196.25) = (477.75 + 76.89) + 196.25
Communicative Property of Addition
16.62 + 4 + 2.38
23
$52.02 - $0.83
$51.19
Round the following number to the underlined digit.
30.125
30.13
The first-place swimmer's time in the 100-meter freestyle at a local swim meet was 1.32 seconds faster than the second-place swimmer who finished in 49.33 seconds. What was the first-place swimmers time?
The first place swimmer's time was 48.01 seconds.