Estimating and Modeling Decimal Sums and Differences

What is a reasonable estimate of the difference between 13.07 and 11.91?

• 24.00

• 1.00

• 5.00

• 7.25

What is a reasonable estimate of the sum of 5.63 and 9.99?

• 5.00

• 5.63

• 16.00

• 2.12

Round to the nearest WHOLE number to find the sum:

44.56 + 14.72

• 59.28

• 50

• 60

• 58

Round to the nearest TEN to find the sum:

19.36 + 12.88

• 32.24

• 31

• 32

• 30

Round to the nearest WHOLE number to find the difference:

324.61 - 211.87

• 113

• 112.74

• 100

• 110

Round to the nearest HUNDRED to find the difference:

576.76 - 231.84

• 200

• 300

• 400

• 344.92

Estimating is finding a value that is CLOSE or APPROXIMATE to the actual value, but it's not exact.

• True

• False

Choose a good pair of compatible numbers to make finding the sum of 223.4 + 148.9 easier to add mentally.

• 200 + 100

• 223 + 149

• 225 + 150

• They're already compatible.

Round to the nearest WHOLE number to find the sum: 34.87 + 20.41

• 55

• 55.28

• 54

• 50

Roughly, approximately, and about are all clues for knowing when to round or estimate.

• True

• False