Estimate Sums Using Rounding

Round each number to the nearest ten. Then find the estimate using the rounded numbers.

24 + 38

• 20 + 40 = 60

• 30 + 30 = 60

• 25 + 35 = 60

• 30 + 40 = 70

Round each number to the nearest ten. Then find the estimate using the rounded numbers.

47 + 56

• 40 + 50 = 90

• 50 + 60 = 110

• 45 + 55 = 100

• 50 + 50 = 100

Tags

CCSS.2.NBT.B.7

CCSS.2.NBT.B.8

Round each number to the nearest ten. Then find the estimate using the rounded numbers.

63 + 29

• 60 + 30 = 90

• 60 + 20 = 80

• 70 + 30 = 100

• 65 + 25 = 90

Tags

CCSS.2.NBT.B.5

CCSS.2.NBT.B.7

Round each number to the nearest ten. Then find the estimate using the rounded numbers.

82 + 19

• 80 + 20 = 100

• 80 + 10 = 90

• 85 + 15 = 100

• 80 + 25 = 105

Tags

CCSS.2.NBT.B.5

CCSS.2.NBT.B.7

CCSS.2.NBT.B.8

Round each number to the nearest ten. Then find the estimate using your rounded numbers.

314 + 421

• 300 + 400 = 700

• 320 + 420 = 740

• 310 + 420 = 730

• 300 + 420 = 720

Tags

CCSS.2.NBT.A.1

CCSS.2.NBT.B.8

Round each number to the nearest ten. and then add the rounded numbers.

569 + 342

• 500 + 300 = 800

• 560 + 340 = 900

• 570 + 340 = 910

• 600 + 300 = 900

Tags

CCSS.2.NBT.A.2

CCSS.2.NBT.B.5

CCSS.2.NBT.B.7

CCSS.2.NBT.B.8

Round 657 to the nearest hundred.

• 600

• 650

• 700

• 660

Tags

CCSS.2.NBT.A.1

CCSS.2.NBT.B.7

CCSS.2.NBT.B.8

Round 149 to the nearest ten.

• 140

• 150

• 100

• 200

Tags

CCSS.2.NBT.A.1

CCSS.2.NBT.B.7

What is the halfway number between 180 and 190?

• 150

• 185

• 195

• 186

Tags

CCSS.2.NBT.B.5

CCSS.2.NBT.B.7

CCSS.2.NBT.B.8

CCSS.2.OA.A.1

Why is it important to use estimation to round numbers before adding or subtracting?

• It is important because it is fun to round numbers.

• It is important because you can find a halfway number.

• It is important because you can use a number line.

• It is important because it helps us to get a quick idea of the answer before we do all of the hard work.

Tags

CCSS.4.NBT.A.3

CCSS.4.OA.A.3