Rounding
Estimate sum
Estimate differences
add 3 digit numbers
subtract 3 digit numbers
100

Round 628 to the nearest ten

630

100

Use rounding to estimate the sum of 23+99=____. Shows work


20+100 = 120

100

Use rounding to estimate the difference. 

92-43=

90-40=50

100

Find the sum use break apart strategy. Show works

545+139=_____

684

100

Estimate. find the sum

679+482=

200

197

200

Round 704 to the nearest hundred 

700 

200

Estimate. Then find the sum 

356+442=____

Estimate: 800

Sum: 798

200

Use rounding to estimate the differences. Show works

445-112=

400-100=300

200

Find the sum using place value strategy. Show works 

437+184=_______

621

200

Estimate. Then find the difference. 

537-123=_______

400

414

300

Round 58 to the nearest hundred 

100

300

Estimate. Then find the sum 

164+230=____


Estimate: 400

Sum: 394

300

Use rounding to estimate differences.

394 - 147=

300

300

Estimate. Then find the sum. Show works

39+243=

Estimate: 40+200=240

Sum: 282

300

Henry H. used 67+38=105 to check his subtraction. Which math problem could he be checking? Mark ALL that apply.

A. 67 - 38=____

B.105 - 67=____

C. 105 +38=____

D. 105 -88=_____

B

400

Emmett planted 77 daisies, 48 roses, and 39 tulips. About how many roses and tulip did he plant than daisies?

About 10 more

400

Andy collected 139 cans for recycling on Monday, and twice that number on Tuesday. How many cans did he collect on Tuesday? Show your work

278 cans

400

During October, 3rd grade decide to have a reading contest and the result as follow. 

Ms. Vy's class      - 273 books 

Mrs. Hong's class - 402 books

Mrs. Ward's class - 247 books 

Select true or false (T/F) for each statement: 

1. Ms. Hong's class read about 100 more books than Ms. Vy's class.   T/F

2. The 3 classes read over 900 books altogether. T/F

3. Mrs. Ward's class read about 50 fewer books than Ms. Vy's class. (T/F)

4. Mrs. Hong's and Mrs. Ward's class read about 700 books. (T/F)


1. True

2. True

3. False

4. False

400

Harper Lynn was making paper flowers for friends. In January, she gave away 246 paper flowers to her family. In February, she gave away 418 paper flowers to her friends. In March, she gave away 349 paper flowers to her neighbors. How many more flowers did she give away in January than March? 

103 paper flowers

400

Marcus has 402 pieces in a building set. He uses 186 pieces to build a house. How many pieces does he have left? Show your work.

216 pieces; 

402 - 186=216

500

Isaac sold 237 cups of lemonade at his lemonade stand. What is 237 rounded to the nearest ten? Include the unit label. 

240 cups

500

There are 294 boys and 332 girls in the NBC school. How many students are in the school?

626 students 

500

Hannah sold 486 muffins at the bake sale. Sawyer sold 287 muffins. Sawyer estimates that he sold 200 fewer muffins than Hannah. How did he estimate? Explain.

Sawyer rounded to the nearest hundred. 


He rounded 486 to 500 and 287 to 300.


Then he subtracted 500-300= 200

500

Delaney was making paper flowers for friends. In January, she gave away 246 paper flowers to her family. In February, she gave away 518 paper flowers to her friends. In March, she gave away 349 paper flowers to her neighbors. How many paper flowers did she give away in January and February? 

764 paper flowers. 

500

Madi solved this problem. She says the difference is 214. Explain the mistake Madi made. What is the correct difference? 


352-148=

She did not combine the right place value numbers. She needs to re-group 1 ten as 10 ones to subtract 48 from 52. The difference is 204