Real-world examples of estimating sums and differences (Grade 2)

📚 Quick Study Guide

• ➕ When estimating sums, round each number to the nearest ten, then add the rounded numbers.
• ➖ When estimating differences, round each number to the nearest ten, then subtract the rounded numbers.
• 💡 Estimating helps you check if your answer is reasonable.
• 🔢 Rounding to the nearest ten means looking at the ones digit. If it's 5 or more, round up. If it's less than 5, round down.
• 📝 Example: Estimate $42 + 37$. $42$ rounds to $40$, and $37$ rounds to $40$. So, the estimated sum is $40 + 40 = 80$.

🤔 Practice Quiz

1. What is the estimated sum of $28 + 53$ when rounded to the nearest ten?
   1. 70
   2. 80
   3. 90
2. What is the estimated difference of $61 - 24$ when rounded to the nearest ten?
   1. 30
   2. 40
   3. 50
3. Sarah has 35 stickers and gives 19 to her friend. About how many stickers does Sarah have left?
   1. 10
   2. 20
   3. 30
4. A book has 48 pages. Tom reads 22 pages. About how many pages are left to read?
   1. 20
   2. 30
   3. 40
5. Estimate: $76 + 12$
   1. 70
   2. 80
   3. 90
6. Estimate: $94 - 31$
   1. 50
   2. 60
   3. 70
7. There are 63 red apples and 28 green apples. About how many apples are there in total?
   1. 70
   2. 80
   3. 90