Reteaching
Name
4-2
Evaluating Addition and
Subtraction Expressions
Find 1.093 1 41.6.
Estimate: Round 1.093 to 1 and 41.6 to 42.
1 1 42 5 43
rite the numbers, lining up the decimal
W
1.093
points. Annex zeros so all numbers have the 41.600 ← Annex 2 zeros.
same number of decimal places.
42.693
42.693 is close to 43, so the answer is
reasonable.
dd the numbers. Regroup if necessary.
A
Write the decimal point in your answer.
Find 18.5 2 g when g 5 7.82.
stimate: Round 7.82 to 8.
E
18.5 2 8 5 10.5
7 4 10
18.50  7.82
10.68
rite the numbers, lining up the decimal
W
points. Annex zeros so all numbers have the
same number of decimal places.
← Annex a zero.
10.68 is close to 10.5, so the answer is
reasonable.
ubtract. Regroup if necessary.
S
Write the decimal point in your answer.
Use substitution to evaluate each expression.
1. 45.6 + 26.3
4. 24.84 2 h; h 5 22.7
7. 3.652 2 a; a 5 1.41
2. n 2 5.14; n 5 14.25
3. 17.2 1 6.08
5. 13.64 2 8.3
6. r 1 15.9; r 5 0.214
8. 18.06 1 9.798
9. t 2 6.38; t 5 8.006
10. Reasonableness Jaime wrote 4.4 2 0.33 5 1.1. Is his answer reasonable?
Why or why not?
R 4•2
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 6