Estimation is your reasonableness check before you compute. You'll catch errors like rounding 4.87 + 3.14 to the nearest ten instead of the nearest whole, claiming 9.52 rounds down to 9, or estimating 7.8 × 4.2 as 28 instead of 32. Fill-ins push you to round 6.49, 3.45, and 11.7 − 4.3, plus estimate 5.1 × 7.9.
A real-world short answer has you decide whether $20 covers a $14.89 shirt and $6.25 socks, and another asks why estimating first is so useful. You'll leave with a sharper sense of when an exact answer looks off.
Style:
Decimal Operations: Add, Subtract, Multiply, Divide
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
To estimate 4.87 + 3.14, round both to the nearest ten: 0 + 0 = 0.
Rewrite: To estimate 4.87 + 3.14, round both to the nearest whole number: 5 + 3 = 8.
2. Fix the sentence:
9.52 rounded to the nearest whole number is 9 because the tenths digit is 5.
Rewrite: 9.52 rounded to the nearest whole number is 10 because the tenths digit 5 means you round up.
3. Fix the sentence:
Estimating 7.8 × 4.2 gives about 28 because 7 × 4 = 28.
Rewrite: Estimating 7.8 × 4.2 gives about 32 because 8 × 4 = 32 when you round 7.8 up to 8.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 6.49 rounded to the nearest whole number is 6.
2. To estimate 11.7 − 4.3, round each to get 12 − 4 = 8.
3. 3.45 rounded to the nearest tenth is 3.5.
4. An estimate for 5.1 × 7.9 using rounding is about 40.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. A shirt costs $14.89 and socks cost $6.25. Estimate the total. Is $20 enough to buy both?
Round to $15 + $6 = $21, so $20 is probably not enough. The exact total is $21.14.
2. Why is estimation useful before computing an exact decimal answer?
Estimation gives a rough answer first, so you can check whether your exact calculation is reasonable and catch mistakes.
Decimal Operations: Add, Subtract, Multiply, Divide
★ Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1) Fix the sentence:
To estimate 4.87 + 3.14, round both to the nearest ten: 0 + 0 = 0.
Rewrite: To estimate 4.87 + 3.14, round both to the nearest whole number: 5 + 3 = 8.
2) Fix the sentence:
9.52 rounded to the nearest whole number is 9 because the tenths digit is 5.
Rewrite: 9.52 rounded to the nearest whole number is 10 because the tenths digit 5 means you round up.
3) Fix the sentence:
Estimating 7.8 × 4.2 gives about 28 because 7 × 4 = 28.
Rewrite: Estimating 7.8 × 4.2 gives about 32 because 8 × 4 = 32 when you round 7.8 up to 8.
★ Part B: Fill in the Blank
Write the missing word or number on each line.
1) 6.49 rounded to the nearest whole number is 6.
2) To estimate 11.7 − 4.3, round each to get 12 − 4 = 8.
3) 3.45 rounded to the nearest tenth is 3.5.
4) An estimate for 5.1 × 7.9 using rounding is about 40.
★ Part C: Short Answer
Answer each question in one or two complete sentences.
1) A shirt costs $14.89 and socks cost $6.25. Estimate the total. Is $20 enough to buy both?
Round to $15 + $6 = $21, so $20 is probably not enough. The exact total is $21.14.
2) Why is estimation useful before computing an exact decimal answer?
Estimation gives a rough answer first, so you can check whether your exact calculation is reasonable and catch mistakes.
Ready to Practice?
Complete each section carefully.
9 Questions
15-20 minutes
Auto-graded
Retry anytime
🏆
Questions Correct
0
Correct
0
Incorrect
0
Skipped
0:00
Time
0%
Score
Review Your Answers
See what you got right, missed, or skipped.