Quick check quiz: Estimating sums and differences by rounding (Grade 3)

📚 Quick Study Guide

🔢 Rounding to the Nearest Ten: Look at the ones digit. If it's 5 or more, round up. If it's 4 or less, round down.
• Example: 47 rounds to 50, 42 rounds to 40.
➕ Estimating Sums: Round each number to the nearest ten, then add the rounded numbers.
• Example: 23 + 38 \(\approx\) 20 + 40 = 60
➖ Estimating Differences: Round each number to the nearest ten, then subtract the rounded numbers.
• Example: 56 - 19 \(\approx\) 60 - 20 = 40
💡 Tips for Success:
• Always pay attention to the digit to the right of the place you are rounding to.
• Practice makes perfect! The more you practice, the easier it will become.
🧐 Why Estimate? Estimating helps you quickly check if your actual answer is reasonable.

Practice Quiz

1. What is 34 + 28 estimated to the nearest ten?
   1. 50
   2. 60
   3. 70
   4. 80
2. What is 67 - 21 estimated to the nearest ten?
   1. 30
   2. 40
   3. 50
   4. 60
3. Estimate 45 + 12 to the nearest ten.
   1. 40
   2. 50
   3. 60
   4. 70
4. Estimate 89 - 33 to the nearest ten.
   1. 40
   2. 50
   3. 60
   4. 70
5. What is the estimated sum of 16 + 52 (rounded to the nearest ten)?
   1. 50
   2. 60
   3. 70
   4. 80
6. Estimate 91 - 48 to the nearest ten.
   1. 30
   2. 40
   3. 50
   4. 60
7. Estimate the sum of 27 + 44 by rounding to the nearest ten.
   1. 50
   2. 60
   3. 70
   4. 80