How do you add whole numbers?

If an artificial coral reef grew 257 inches last year and 567 inches this year, how much did it grow in all?

Estimate: 300 + 600 = 900

Another Example
How do you add more than two numbers?

Find the sum.
9,348 + 102 + 5,802 + 1,933
A. 17,185
B. 17,175
C. 16,175
D. 15,175

Estimate: 9,000 + 100 + 6,000 + 2,000 = 17,100

Step 1

Regroup if necessary

Step 2

Regroup if necessary.

Step 3

Explain It

Question 1.
How are the ones regrouped in the example above?

Question 2.
Reasonableness In Step 3 above, how can you tell that the answer is reasonable?

Step 1

Regroup if necessary.

Step 2

Regroup if necessary.

Step 3
Add the hundreds. Regroup if necessary

The reef grew 824 inches in all.

Other Examples

Estimate:
36,000 + 25,000 = 61,000

The sum is reasonable because it is close to the estimate of 61,000.

Add 130,283 + 263,823 + 396,538.
Estimate:
130,000 + 264,000 + 397,000 = 791,000

The sum is reasonable because it is close to the estimate of 791,000.

Guided Practice*

In 1 through 6, find each sum.

Question 1.
821 + 4,543

Question 2.
14,926 + 3,832

Question 3.
1,321 + 2,246

Question 4.
24,593 + 16,861

Question 5.

Question 6.

Do You Understand?

Question 7.
When adding 36,424 and 24,842 above, why is there no regrouping in the 2nd step?

Question 8.
Volunteer teams identified 73 fish species, 30 corals, and 71 other invertebrates on the reef. How many species of fish, coral, and
invertebrates were found in all?

Independent Practice

In 9 through 24, find each sum.

Question 9.

Question 10.

Question 11.

Question 12.

Question 13.

Question 14.

Question 15.

Question 16.

Question 17.

Question 18.

Question 19.
9,634 + 2,958

Question 20.
4,673 + 262

Question 21.
7,845 + 509 + 3,746

Question 22.
526 + 276 + 1,086

Question 23.
2,868 + 865

Question 24.
15,891 + 527 + 1,086

Problem Solving

Question 25.
In 1972, the Apollo 16 lunar rover set the current lunar speed record at 11 miles per hour. In order to break free from Earth’s orbit, Apollo missions had to go 24,989 miles per hour faster than the record speed of the lunar rover. How fast did the Apollo rockets travel?

Question 26.
There were 10,453 items checked out of the public library one week. The next week 12,975 items were checked out. A week later, 9,634 items were checked out. How many items were checked out in three weeks?

Question 27.
Sandy read 235 pages of a book. She had 192 more pages to read before she was done. How many pages are there in the book?

Question 28.
Cheryl and Jason collect baseball cards. Cheryl has 315 cards, and Jason has 186 cards. How many cards do they have altogether?

Question 29.
Number Sense The sum of 86, 68, and 38 is 192. What do you know about the sum of 68, 38, and 86?

Question 30.
Estimation Maria added 45,273 and 35,687. Will her answer be greater or less than 80,000?

Question 31.
The population of New City is 23,945. Eastdale has a population of 12,774. What is the total population of the two communities?
A. 35,719
B. 36,619
C. 36,719
D. 37,619

Mixed Problem Solving

Question 1.
Estimate how much higher Mount Shasta is than Lassen Peak.

Question 2.
Estimate how much higher above sea level Mount Whitney is than the depth of Death Valley.

Question 3.
Estimate the range of the width of Death Valley.

Question 4.
Estimate how many years the Spanish governed California.

Question 5.
Estimate which group governed California for a longer period of time: the Spanish government or the Mexican government.

Question 6.
About how many years has the United States been governing the State of California?