Estimating Fractions and Decimals Review Quiz

Round each number to the nearest whole number and solve. 7.49 + 8.51 + 12.3

• 28

• 27

• 29

• 30

Answer explanation

Round 7.49 to 7, 8.51 to 9, and 12.3 to 12. Adding these gives 7 + 9 + 12 = 28. Therefore, the correct answer is 28.

Estimate the sum to the nearest whole number. 15 1/3 + 22 5/6

• 38

• 39

• 40

• 41

Answer explanation

To estimate the sum, convert the mixed numbers to improper fractions: 15 1/3 is approximately 15 (because 1/3 is less than half) and 22 5/6 is about 23 (because 5/6 is more than half). Adding these gives roughly 38. Thus, the correct answer is 38.

Arjun is baking a cake and needs to measure two ingredients. The first ingredient is 45 3/4 cups and the second ingredient is 18 1/3 cups. Estimate the difference in their measurements to the nearest whole number.

• 28

• 27

• 26

• 29

Answer explanation

To estimate, round 45 3/4 to 46 and 18 1/3 to 18. The difference is 46 - 18 = 28. Thus, the estimated difference in their measurements is 28, which is the correct choice.

Estimate the difference to the nearest tenth. 47.89 - 12.45

• 35.4

• 36.4

• 34.4

• 33.4

Answer explanation

To estimate 47.89 - 12.45, round to the nearest tenth: 47.89 rounds to 47.9 and 12.45 rounds to 12.5. Now, calculate 47.9 - 12.5 = 35.4. Thus, the estimated difference is 35.4.

Tom is sewing a quilt and wants to use two different fabrics for the pattern. He has 1 3/4 yards of one fabric and 2 1/4 yards of another fabric. Approximately how much fabric does he have in total?

• 3 yards

• 4 yards

• 5 yards

• 6 yards

Answer explanation

To find the total fabric, convert the mixed numbers: 1 3/4 is about 2 (because 3/4 is more than half) and 2 1/4 is about 2 (because 1/4 is less than half). Adding them gives 2 + 2 = 4 yards. Therefore, Tom has approximately 4 yards of fabric.

Estimate and Solve 
7   4/5  + 11  1/10

• 18

• 19

• 20

Answer explanation

To estimate, round 7 4/5 to 8 and 11 1/10 to 11. Adding these gives 8 + 11 = 19. Thus, the correct answer is 19.

Tags

CCSS.4.NBT.B.4

CCSS.4.NF.C.5

CCSS.4.OA.A.3

Estimate and solve:

7 4/8 + 2 8/10

• 10

• 4

• 11

• 4 1/2

Answer explanation

To estimate, round 7 4/8 to 8 (because 4/8 is exactly one half and that rounds up the fraction to 1) and 2 8/10 to 3 (because 8/10 is more than 1/2). Adding these gives approximately 11. The exact sum is 8 + 3 = 11. Thus, the correct answer is 11.

Tags

CCSS.3.NBT.A.2

CCSS.3.NF.A.1

CCSS.3.OA.D.8

When rounding, what numbers tell you to round up?

• 2,4,6,8, and 0

• 0.1,2,3,and 4

• 5,6,7,8, and 9

Answer explanation

When rounding, you round up if the digit in the place you are rounding to is 5 or higher. Therefore, the correct choice is 5, 6, 7, 8, and 9, as these numbers indicate to round up.

When rounding, what fraction tells you to round up to the next whole number?

• 1/4

• 2/3

• 1/2

Answer explanation

When rounding, if the fraction is 1/2 or higher, you round up to the next whole number. This means that 1/2 is the fraction that indicates you should round up, making it the correct choice.

Estimate the sum to the nearest whole number. 9 2/5 + 14 3/5

• 23

• 24

• 25

• 26

Answer explanation

To estimate, round 9 2/5 to 9 and 14 3/5 to 15. Adding these gives 9 + 15 = 24. Thus, the nearest whole number for the sum 9 2/5 + 14 3/5 is 24.