Examples of estimating sums in word problems (Grade 5)

📚 Quick Study Guide

• ➕ Rounding: Round each number in the word problem to the nearest ten, hundred, or thousand, depending on the size of the numbers. This makes the addition easier to perform mentally.
• 🤝 Compatible Numbers: Look for numbers that are easy to add together. For example, if you have 26 and 74, think of them as 25 and 75.
• 🧠 Mental Math: After rounding or finding compatible numbers, add the rounded numbers mentally to estimate the sum.
• 📝 Checking for Reasonableness: Does your estimate make sense in the context of the word problem? Always double-check!

➕ Practice Quiz

1. What is the estimated sum of 34 + 57 when rounding to the nearest ten?
   1. 70
   2. 80
   3. 90
   4. 100
2. A store sold 123 apples and 289 oranges. Estimate the total number of fruits sold by rounding to the nearest hundred.
   1. 300
   2. 400
   3. 500
   4. 600
3. Sarah wants to buy a book for $18 and a pen for $4. Estimate the total cost by rounding to the nearest ten.
   1. $10
   2. $20
   3. $25
   4. $30
4. There are 45 students in class A and 32 students in class B. What is the estimated total number of students when rounding to the nearest ten?
   1. 60
   2. 70
   3. 80
   4. 90
5. A farmer harvested 245 tomatoes and 351 peppers. Estimate the total harvest by rounding to the nearest hundred.
   1. 400
   2. 500
   3. 600
   4. 700
6. John wants to buy a shirt for $27 and pants for $42. Estimate the total cost by using compatible numbers.
   1. $60
   2. $65
   3. $70
   4. $75
7. A bakery sold 195 cookies and 203 muffins. Estimate the total number of items sold by rounding to the nearest hundred.
   1. 300
   2. 350
   3. 400
   4. 450