Students correct three addition and subtraction errors — not aligning decimal points, a place-value subtraction error, and a carrying mistake. Part B has four questions about decimal addition, subtraction, and rewriting with equal decimal places. Part C has two questions about why decimal alignment matters and how to subtract 4.7 from 10.25.
Correcting misalignment errors and place-value errors in decimal addition and subtraction builds the procedural accuracy students need before multiplying or dividing decimals.
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:
3.5 + 2.14 = 5.19 because you just add left to right.
Rewrite: 3.50 + 2.14 = 5.64 because you must align decimal points and add by place value.
2. Fix the sentence:
7.8 − 3.25 = 4.45 since 80 minus 25 is 45.
Rewrite: 7.80 − 3.25 = 4.55 since 80 hundredths minus 25 hundredths is 55 hundredths.
3. Fix the sentence:
12.6 + 9.47 = 21.07 because 6 + 47 = 107.
Rewrite: 12.60 + 9.47 = 22.07 because 60 + 47 = 107 hundredths, carry 1 to the ones place.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 4.32 + 1.57 = 5.89
2. 9.05 − 3.72 = 5.33
3. When adding 6.3 + 2.48, rewrite 6.3 as 6.30 so both have the same decimal places.
4. 15.00 − 7.63 = 7.37
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Why is it important to align decimal points before adding or subtracting?
Aligning decimal points ensures you add digits with the same place value, like tenths with tenths.
2. Explain how to subtract 4.7 from 10.25.
Rewrite 4.7 as 4.70, then subtract: 10.25 − 4.70 = 5.55, regrouping as needed.
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:
3.5 + 2.14 = 5.19 because you just add left to right.
Rewrite: 3.50 + 2.14 = 5.64 because you must align decimal points and add by place value.
2) Fix the sentence:
7.8 − 3.25 = 4.45 since 80 minus 25 is 45.
Rewrite: 7.80 − 3.25 = 4.55 since 80 hundredths minus 25 hundredths is 55 hundredths.
3) Fix the sentence:
12.6 + 9.47 = 21.07 because 6 + 47 = 107.
Rewrite: 12.60 + 9.47 = 22.07 because 60 + 47 = 107 hundredths, carry 1 to the ones place.
★ Part B: Fill in the Blank
Write the missing word or number on each line.
1) 4.32 + 1.57 = 5.89
2) 9.05 − 3.72 = 5.33
3) When adding 6.3 + 2.48, rewrite 6.3 as 6.30 so both have the same decimal places.
4) 15.00 − 7.63 = 7.37
★ Part C: Short Answer
Answer each question in one or two complete sentences.
1) Why is it important to align decimal points before adding or subtracting?
Aligning decimal points ensures you add digits with the same place value, like tenths with tenths.
2) Explain how to subtract 4.7 from 10.25.
Rewrite 4.7 as 4.70, then subtract: 10.25 − 4.70 = 5.55, regrouping as needed.
Ready to Practice?
Complete each section carefully.
9 Questions
15-20 minutes
Auto-graded
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