This grade 3 rounding test answer key gives the full solution and the scoring guide for each of the 9 test questions on rounding to the nearest 10 and 100.
Use this key to score the test out of 20 points. Each solution shows the digit that decides the rounding, and the scoring note tells how to give partial credit.
Grade 3 Rounding Test Answer Key: questions 1–5
Question 1: Nearest 10 (3 points)
- \(47\) rounds to \(50\).
- \(135\) rounds to \(140\).
- \(598\) rounds to \(600\).
Scoring: 1 point for each correct number. 135 must be 140 and 598 must be 600.
Question 2: Nearest 100 (3 points)
- \(214\) rounds to \(200\).
- \(650\) rounds to \(700\).
- \(972\) rounds to \(1,000\).
Scoring: 1 point for each correct number.
Question 3: Number line check (2 points)
- 73 is before the halfway mark 75, so it rounds to 70.
- 75 is exactly halfway: it is 5 away from 70 and 5 away from 80. The rule says halfway rounds up, so it rounds to 80.
Scoring: 1 point for 70. 1 point for explaining that 75 is halfway and rounds up to 80.
Question 4: One number, two roundings (2 points)
- The ones digit is 3, so 483 rounds to \(480\).
- The tens digit is 8, so the hundreds digit 4 goes up: 483 rounds to \(500\).
Scoring: 1 point for each correct rounded number.
Question 5: Cards that round to 500 (2 points)
449 → 400, 450 → 500, 538 → 500, 551 → 600, 549 → 500.
The numbers are 450, 538, and 549.
Scoring: 2 points for all three numbers and no extras. 1 point for two correct numbers with no extras, or for all three plus one extra.
Grade 3 Rounding Test Answer Key: questions 6–9
Question 6: Estimate and check (2 points)
- 62 → 60 and 29 → 30, so \(60 + 30 = 90\). The estimate is 90.
- \(62 + 29 = 91\). The estimate is 1 less than the exact sum.
Scoring: 1 point for the estimate. 1 point for the exact sum and the difference of 1.
Question 7: Numbers that round to 70 (2 points)
65 rounds up to 70, while 64 rounds down to 60. 74 rounds to 70, while 75 rounds up to 80.
Smallest: 65. Greatest: 74.
Scoring: 1 point for each correct number.
Question 8: Weekend drive (2 points)
- 178 → 200 and 226 → 200, so \(200 + 200 = 400\) miles.
- \(178 + 226 = 404\) miles. The estimate is 4 miles less than the exact total.
Scoring: 1 point for the estimate of 400. 1 point for 404 and the difference of 4.
Question 9: Find the mistake (2 points)
Mei looked at the 9 in the ones place. To round to the nearest 100, she should look at the tens digit, which is 4. Since 4 is less than 5, the hundreds digit stays the same.
The correct answer is 700.
Scoring: 1 point for explaining that the tens digit decides. 1 point for 700.
Scoring summary
20 points: add the points of every question of this grade 3 rounding test answer key.
How to use this grade 3 rounding test answer key
Use this grade 3 rounding test answer key to score the test fairly and to see which skills need more practice.
Printable PDF · Test Answer Key
Grade 3 Rounding to the Nearest 10 and 100 test answer key
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