Question

lesson 4-1
additional practice
name
review
you can estimate sums and differences of decimals.
seth has $50 to spend at a store. he purchases a sweater that costs $18.75 and a shirt that costs $9.05. about how much will seth have left to spend?
first estimate the sum 18.75 + 9.05 to find how much seth spends.
use rounding to estimate each amount.
18.75 + 9.05
19 + 9 = 28
then subtract to find the amount he has left: 50 − 28 = 22.
seth will have about $22 left to spend.
estimate each sum or difference.

1. 8.41 + 2.77 = ?

__ + = __

1. 14.38 − 4.85 = ?

__ − = __

1. 11.2 + 7.79 = ?

__ + = __

1. 33.12 − 16.8 = ?

__ − = __

1. 14.18 + 21.08 = ?

__ + = __

1. 78.58 − 49.72 = ?

__ − = __

1. 24.61 + 19.09 = ?

__ + = __

1. 64.47 − 28.01 = ?

__ − = __

Explanation:

Step1: Estimate 8.41 + 2.77

Round 8.41 to 8 and 2.77 to 3.
$8 + 3 = 11$

Step2: Estimate 14.18 + 21.08

Round 14.18 to 14 and 21.08 to 21.
$14 + 21 = 35$

Step3: Estimate 14.38 - 4.85

Round 14.38 to 14 and 4.85 to 5.
$14 - 5 = 9$

Step4: Estimate 78.58 - 49.72

Round 78.58 to 79 and 49.72 to 50.
$79 - 50 = 29$

Step5: Estimate 11.2 + 7.79

Round 11.2 to 11 and 7.79 to 8.
$11 + 8 = 19$

Step6: Estimate 24.61 + 19.09

Round 24.61 to 25 and 19.09 to 19.
$25 + 19 = 44$

Step7: Estimate 33.12 - 16.8

Round 33.12 to 33 and 16.8 to 17.
$33 - 17 = 16$

Step8: Estimate 64.47 - 28.01

Round 64.47 to 64 and 28.01 to 28.
$64 - 28 = 36$

Answer:

1. Estimate: \(8 + 3 = 11\)
2. Estimate: \(14 + 21 = 35\)
3. Estimate: \(14 - 5 = 9\)
4. Estimate: \(79 - 50 = 29\)
5. Estimate: \(11 + 8 = 19\)
6. Estimate: \(25 + 19 = 44\)
7. Estimate: \(33 - 17 = 16\)
8. Estimate: \(64 - 28 = 36\)

(Note: For exact values, calculate without rounding:

1. \(8.41 + 2.77 = 11.18\)
2. \(14.18 + 21.08 = 35.26\)
3. \(14.38 - 4.85 = 9.53\)
4. \(78.58 - 49.72 = 28.86\)
5. \(11.2 + 7.79 = 18.99\)
6. \(24.61 + 19.09 = 43.7\)
7. \(33.12 - 16.8 = 16.32\)
8. \(64.47 - 28.01 = 36.46\))