3rd Grade Topic 8 Envision- Use Strategies and Properties to Add and Subtract

Addition Properties

100

Which property says

"The sum of zero and any number is the same number?"

Identity Property

200

Which property is illustrated by the number sentence below?

893+0=893

Identity Property

300

Which property says 

"You can group addends in any way and the sum will be the same and the numbers remain in the same order?"

Associative Property

400

Use the addition properties to find the missing number.

7+(2+____)=(7+____)+3

7+(2+__3__)=(7+_2___)+3

500

What is a number sentence that illustrates the commutative property?

65+0=65

214+159=159+214

(25+120)+300=25+(120+300)

214+159=159+214

Rounding

100

Round 78 to the tens place

80

200

Round 429 to the hundreds place

400

300

Round 364 to the nearest ten.

360

400

Round 551 to the nearest hundred.

600

500

Rounding 383 to the nearest ten and hundred.

ten- 380

hundred 400

Estimating Sums

100

Round to the nearest ten to estimate

344+571

340+570=910

200

Round to the nearest 10 to estimate the sum.

269+322

270+320=590

300

Round to the nearest hundred to estimate.

462+175=

500+200=700

400

Find a reasonable estimate for the sum of 383 and 449. Select all that apply.

       390 + 450 = 840
       400 + 400 = 800
       380 + 450 = 830
       300 + 400 = 70

400 + 400 = 800
380 + 450 = 830

500

Mrs. McCann drove from Charleston to St. Louis and back again. It is 133 miles to Chicago. To the nearest hundred miles, about how many miles in all did she drive? 

133-----100

100+100= 200

Estimating Differences

100

Round to the nearest ten to estimate.

825-213

825-----830

213-----210

830-210=620

200

Round to the nearest 10 to estimate the difference.

436-278

436-----440

278-----280

440-280= 160

300

Round to the nearest hundred to find the difference.

493 – 261= _________

493-----500

261----300

500-300=200

400

A train left the terminal with 78 passengers. At the first stop, 42 passengers got off the train, and no passengers got on the train. How many passengers were left on the train? ESTIMATE THE DIFFERENCE.

78-----80

42-----40

80-40= 40

500

Katie lives 492 miles away from her grandparents. Her cousin, Sarah, lives 39 miles from her grandparents. To the nearest ten, about how many more miles does Katie live from her grandparents, than Sarah does?

490-40=450

Mental Math/Number Line

100

Find the sum using mental math or an open number line. Show your work.

123 + 489 = ______

123=100+20+3

489+100=589

589+20=609

609+3=612

200

. Use an open number line or mental math to find the difference. Show your work.

952 – 345= _________

345=300+40+5

952-300=652

652-40=612

612-5=607

300

. Use an open number line or mental math to find the sum. Show your work.

302+56= _________

56=50+6

302+50=352

352+6=358

400

. Use an open number line or mental math to find the difference. Show your work.

493 – 261= _________

261=200+60+1

493-200=293

293-60=233

233-1=232

500

Find the sum using mental math or an open number line. Show your work.

349 + 253 = ______

200+50+3

349+200=549

549+50=599

599+3=602