Estimation and Rounding — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A Grade 4 student calculates 387 + 412 = 1,299. Use estimation to check. Is the answer reasonable?
A) Yes, it is correct
B) No, the estimate is about 800
C) No, the estimate is about 1,500
D) Cannot tell
Rounded, 400 + 400 = 800, but the student's answer 1,299 is far from 800, so it is unreasonable.
2. A Grade 4 estimate of 612 - 198 to the nearest 100 is closest to which value?
A) 300
B) 400
C) 500
D) 600
Rounded, 600 - 200 = 400, near the actual 414.
3. A school store sold 2,856 pencils. About how many pencils, rounded to the nearest 1,000? (Grade 4)
A) 2,000
B) 3,000
C) 2,800
D) 2,900
Since 8 is 5 or more, 2,856 rounds up to 3,000.
4. A Grade 4 student says 528 x 5 is about 3,000. Which estimate did they likely use?
A) 500 x 5 = 2,500
B) 600 x 5 = 3,000
C) 500 x 6 = 3,000
D) 1,000 x 3 = 3,000
Rounded up, 600 x 5 = 3,000 matches the estimate, and is reasonable since the actual product is 2,640.
Part B: Fill in the Blank
Write the correct answer on each line.
1. Grade 4 estimate: 489 x 4 using rounding is about 2000.
Rounded, 500 x 4 = 2,000, near the actual 1,956, so it is reasonable.
2. A Grade 4 estimate of 7,491 to the nearest 1,000 is 7000.
Since 4 is less than 5, 7,491 rounds down to 7,000.
3. Grade 4 estimate: 3,612 + 5,489 to nearest 1,000 is about 9000.
Rounded, 4,000 + 5,000 = 9,000, near the actual 9,101.
4. A Grade 4 student finds 612 - 287 = 325. Their estimate to nearest 100 is 300.
Rounded, 600 - 300 = 300, close to the actual 325, so the answer is reasonable.
5. Grade 4: 4,950 rounded to the nearest 1,000 is 5000.
Since 9 is 5 or more, 4,950 rounds up to 5,000.