Unit 2 Review

Unit 2 Review

Topic D Lesson

Objective: I'll be able to round numbers to the

nearest 10 or 100 to estimate the sum of two big

numbers.

Estimate to add Multi-Digit Whole

Numbers

Why do we round?

estimating sums helps us quickly find an approximate answer by rounding
numbers.

398 rounded to the nearest 100 is 400 and 251 to 250 .

Think, Pair, Shair

523+678 : Round each number to the nearest 100 and estimate
the sum.

523 to 500 and 678 to 700 , then
adding to get 1200 .

Break Apart 3-Digit Addition Problems

Math Response

Break apart 352 + 175

Type answer here

Correct Answer: \left(300+100\right)+\left(50+70\right)+\left(2+5\right)

Deg^°

Rad

Why do we break apart numbers?

Breaking apart numbers helps simplify addition by focusing
on place values: hundreds, tens, and ones.

Break down each number:

● 374=300+70+4
● 152=100+50+2

this method
makes it easier to
add each place
value separately.

374 + 152

1.

Add Hundreds: 300 + 100 = 400

2.

Add Tens: 70 + 50 = 120

3.

Add Ones 4 + 2 = 6

400 + 120 + 6 = 526

"Imagine you have 452 stickers and your friend gives
you 326 more. How many stickers do you have
now?" Use the “break apart” method to solve.

1.Break down:

452=400+50+2

326=300+20+6

2. Add each place
value:

Hundreds: 400+300 =700

Tens: 50+20 =70

Ones: 6+2 =8

3. Combine

700+70+8=778