## Envision Math 4th Grade Textbook Answer Key Topic 2.4 Estimating Sums and Differences of Whole Numbers

Estimating Sums and Differences of Whole Numbers

How can you estimate sums and differences of whole numbers?

The Empire State Building was completed in 1931. From ground to tip, it measures 1,250 feet. At the top of the building is a lightning rod which measures 204 feet. Estimate the total height of the structure. Guided Practice*

Do you know HOW?

In 1 through 6, estimate each sum or difference.

Question 1. Question 2. Question 3.
645 + 253

Question 4.
262 – 132

Question 5.
952 – 402

Question 6.
398 + 121

Do You understand?

Question 7.
Writing to Explain In the first example above, why can’t you round both numbers to the nearest thousand?

Question 8.
The Statue of Liberty was completed in 1886. About how many years later was the Empire State Building completed than the Statue of Liberty?

Independent practice

In 9 through 16, estimate by rounding to the nearest ten.

Question 9. Question 10. Question 11. Question 12. Question 13.
738 + 741

Question 14.
895 – 305

Question 15.
755 – 344

Question 16.
586 + 278

In 17 through 24, estimate by rounding to the nearest hundred.

Question 17. Question 18. Question 19. Question 20. Question 21.
423 + 196

Question 22.
891 + 223

Question 23.
1,724 – 731

Question 24.
551 – 249

Round each number to the nearest hundred. The total height is about 1,500 feet.
The answer is reasonable because the total height is greater than the height of the Empire State Building.

The Washington Monument was completed in 1884. About how many years after was the Empire State
Building completed? The Empire State Building was completed about 50 years later.

Problem Solving

Question 25.
The time line below shows the years that the Big Basin Redwoods State Park and the Mount Diablo State Park opened to the public. Use the time line to estimate the difference in years between the time they opened. Question 26.
This year, 35,658 people ran in a marathon. Last year, 8,683 fewer people ran. About how many people
ran last year?

Question 27.
During swimming practice, Juan swam 15 laps and Ted swam 9 laps. How many more laps did Juan swim
than Ted?