Vocabulary
To align decimal points in a decimal addition problem, annex zeros to write _______ so that all addends have the same number of decimal places.
equivalent decimals
Estimate by rounding to the nearest whole number.
28.65+10.23
29+10=39
3.4+2.6=
3.4+2.6=6.0
7.5-2.3=
7.5-2.3=5.2
Ed is training for a race. He ran 12.56 miles on one day, 12.98 the second, and 13.04 miles on the third day. How much did he run in all the days?
38.58 miles
You can replace the values in a problem with _______ so that it's easier to use mental math to complete the computation.
Compatible numbers
Estimate by rounding to the nearest hundred.
358+293
400+300=700
12.75+3.25=
12.75+3.25=16.00
$10-$4.75=
$10-$4.75= $5.25
The Thomas Jefferson Memorial is on 18.36 acres of land, the Franklin D Roosevelt Memorial is on 7.5 acres of land, the Vietnam Veterans Memorial is on 8.9 acres of land, and the World War I Memorial is on 9.6 acres of land. Which two memorials have the greatest difference in area? What is this difference?
Thomas Jefferson Memorial and Franklin D Roosevelt Memorial
18.36-7.5=10.86
When you adjust one number and change another number in the problem to make a computation easier, you use _______.
Compensation
Estimate by rounding to the nearest tenth.
15.65+6.45=
15.7+6.5 = 22.2
5.08+7.9=
5.08+7.9=12.98
15.6-8.49=
15.6-8.49=7.11
Amber bought a hardcover book for $23.70 and a paperback for $6.91. If she gave the cashier $40, how much change did she get?
23.70+6.91=30.61
40-30.61=$9.39
Commutative Property of Addition
Estimate by rounding to the nearest tenth.
14.65-12.15
14.7-12.2= 6.5
$4.65+$2.35=
$4.65+$2.35=$7.00
12.35-7.8=
12.35-7.8=4.55
Kassandra has a rectangular patio in her backyard. The patio is 12.74 meters long and 5.45 meters wide. What is the perimeter of her patio?
5.45+5.45+12.74+12.74=36.38
Because of the ___________, I know that (477.75 + 76.89) + 196.25 = 477.75 + (76.89 + 196.25)
Associative Property of Addition
Estimate by rounding to the nearest hundredth.
452.871+763.384
452.87+763.38=1216.25
23.456+7.89=
23.456+7.89=31.346
50.007-23.89=
50.007-23.89=26.117
Mr.Lee sold 8.6 pounds of apples, Ms. Perry sold 40.44 pounds of apples, Ms. Cleary sold 23.5 pounds of apples, and Mr. Jones sold 34.5 pounds of apples at the farmers market. Which two people sold the most apples? What is the difference between the amounts these people sold?
40.44-34.5=5.94