Estimating Addition and Subtraction of Fractions-Gr 5-Solved Examples

Solved Examples and Worksheet for Estimating Addition and Subtraction of Fractions

Q1Estimate:

$32$ -

$817$
A. 1
B. 17
C. 2
D. 3

Solutions

Step: 1

$32$

$≈$ 1

[Round to the nearest half.]

Step: 2

$817$

$≈$ 0

[Round to the nearest half.]

Step: 3

$32$ -

$817$

$≈$ 1 - 0

[Subtract the fractions.]

Step: 4

$≈$ 1

Correct Answer is : 1

Q2Estimate:

$2372$ +

$663$

A. 0
B. 6
C. 23
D. 72

Solutions

Step: 1

$2372$ +

$663$

$≈$ 0 + 0

[Round to the nearest half.]

Step: 2

= 0

[Add.]

Step: 3

$2372$ +

$663$

$≈$ 0

Correct Answer is : 0

Q3Estimate the sum of

$1626$ and

$3262$ .

A.

$112$
B.

$12$
C. 2
D. 1

Solutions

Step: 1

$1626$

$≈$

$12$ and

$3262$

$≈$

$12$

[Round the fractions to

$12$ as the denominators are nearly twice the numerators.]

Step: 2

$1626$ +

$3262$

$≈$

$12$ +

$12$ = 1

[Add the fractions.]

Correct Answer is : 1

Q4Estimate.

$35$ -

$14$
A. 0
B. 2
C. 3
D. 1

Solutions

Step: 1

$35$

$≈$ 1

[Round to 1, if the numerator almost equals the denominator.]

Step: 2

$14$

$≈$ 0

[Round to 0, if the numerator is close to 0.]

Step: 3

$35$ -

$14$

$≈$ 1 - 0 = 1

[Round the fractions and subtract.]

Step: 4

Therefore,

$35$ -

$14$

$≈$ 1.

Correct Answer is : 1

Q5Estimate.

$27$ -

$19$
A. 1
B. 2
C. 0
D. 3

Solutions

Step: 1

$27$

$≈$ 0

[Round to 0, if the numerator is close to 0.]

Step: 2

$19$

$≈$ 0

[Round to 0, if the numerator is close to 0.]

Step: 3

$27$ -

$19$

$≈$ 0 - 0 = 0

[Round the fractions and subtract.]

Step: 4

Therefore,

$27$ -

$19$

$≈$ 0.

Correct Answer is : 0

Q6Alice buys a sack of potatoes that weighs

$118$ lb and a sack of tomatoes that weighs

$127$ lb. Estimate the total weight of the vegetables.

A. 2 lb
B.

$138$ lb
C.

$312$ lb
D. 4 lb

Solutions

Step: 1

Weight of potatoes =

$118$ lb

Step: 2

$118$

$≈$ 1

[

$18$ is close to 0.]

Step: 3

Weight of tomatoes =

$127$ lb

Step: 4

$127$

$≈$ 1

[

$27$ is close to 0.]

Step: 5

Total weight of vegetables = Weight of potatoes + Weight of tomatoes

Step: 6

= 1 + 1 = 2

[Substitute the values and add.]

Step: 7

So, the weight of the vegetables is about 2 lb.

Correct Answer is : 2 lb

Q7Estimate the sum of

$511$ and

$1011$ .
A.

$112$
B.

$10111$
C.

$11011$
D.

$2111$

Solutions

Step: 1

$511$

$≈$

$12$

[Round to the nearest half.]

Step: 2

$1011$

$≈$ 1

[Round to the nearest half.]

Step: 3

$511$ +

$1011$

[Sum of the fractions.]

Step: 4

$≈$

$12$ + 1

Step: 5

$≈$

$112$

[Add the rounded fractions.]

Correct Answer is :

$112$

Q8Estimate the sum of

$78$ and

$56$ .

A. 4
B. 3
C. 2
D. 1

Solutions

Step: 1

$78$

$≈$ 1

[Round to 1, if the numerator almost equals the denominator.]

Step: 2

$56$

$≈$ 1

[Round to 1, if the numerator almost equals the denominator.]

Step: 3

1 + 1 = 2

[Round the fractions and add.]

Step: 4

$78$ +

$56$

$≈$ 1 + 1 = 2

[Round the fractions and add.]

Step: 5

Therefore,

$78$ +

$56$

$≈$ 2.

Correct Answer is : 2

Q9Mary has two sewing needles. The length of one needle is

$1112$ in. and the length of another needle is

$178$ in. Estimate the sum of the lengths of the two needles.
A.

$113$ in.
B. 1 in.
C. 3 in.
D. 2 in.

Solutions

Step: 1

Length of the first needle =

$1112$ in.

$≈$ 1 in.

Step: 2

Length of the second needle =

$178$ in.

$≈$ 2 in.

Step: 3

The sum of the two needles = 1 + 2 = 3 in.

Step: 4

So, the total length of the two needles is about 3 in.

Correct Answer is : 3 in.

Q10John traveled a distance of

$5059$ km by his bike and car. He traveled

$2079$ km by his bike. Estimate the distance he traveled by car.

A. 26 km
B. 30 km
C. 20 km

Solutions

Step: 1

$5059$

$≈$ 51

[Because

$59$ >

$12$ , round up to 51.]

Step: 2

$2079$

$≈$ 21

[Because

$79$ >

$12$ , round up to 21.]

Step: 3

$5059$ -

$2079$

$≈$ 51 - 21 = 30

[Subtract.]

Step: 4

So, John traveled about 30 km by car.

Correct Answer is : 30 km

Solved Examples and Worksheet for Estimating Addition and Subtraction of Fractions

Related Worksheet

Related Topic

HighSchool Math