Review for Review for Chapter 7 Chapter 7

Multiply by Two-digit Multiply by Two-digit NumbersNumbers

7.1: Multiply by powers of 107.1: Multiply by powers of 10

Use mental math to help you multiply.Use mental math to help you multiply.

8 x 60 =8 x 60 = 80 x 60 =80 x 60 = 80 x 600 =80 x 600 = 80x 6,000 =80x 6,000 =

4804,80048,000480,000

7.1: Multiply by powers of 107.1: Multiply by powers of 10

Use mental math to help you multiply.Use mental math to help you multiply.

5 x 60 =5 x 60 =

50 x 60 =50 x 60 =

50 x 600 =50 x 600 =

50x 6,000 =50x 6,000 =

3003,00030,000300,000

7.2: Use rounding to estimate 7.2: Use rounding to estimate productsproducts

Estimate the product by rounding each factor to its Estimate the product by rounding each factor to its greatest place.greatest place.

3434

x23x23

30 ( I rounded 34 to 30) x20 ( I rounded 23 to 20)600 is my estimate

7.2: Use rounding to estimate 7.2: Use rounding to estimate productsproducts

Estimate the product by rounding each factor to its Estimate the product by rounding each factor to its greatest place.greatest place.

77 x 9577 x 95

80 x 100 = 8,000

I rounded 77 to 80 and 95 to 100 and then used my mental math strategy to multiply.

7.2: Use rounding to estimate 7.2: Use rounding to estimate productsproducts

Estimate the product by rounding each factor to its Estimate the product by rounding each factor to its greatest place.greatest place.

9,7099,709

xx 35 35

10,000 ( I rounded 9,709 to 10,000)X 40 ( I rounded 35 to 40)

My best estimate is 400,000

7.3: Use base-ten blocks to model 7.3: Use base-ten blocks to model multiplication.multiplication.

Tell what multiplication sentence is shown by the array.Tell what multiplication sentence is shown by the array.

Then find the productThen find the product

11 x 6 = 66

7.3: Use base-ten blocks to model 7.3: Use base-ten blocks to model multiplication.multiplication.

Tell what multiplication sentence is shown by the array.Tell what multiplication sentence is shown by the array.

Then find the productThen find the product

19 x 16 = 304

7.4: Multiply two-digit numbers.7.4: Multiply two-digit numbers.

Multiply. Show your work.Multiply. Show your work.

36 36

xx1717

36 x17 252 360 612

7.4: Multiply two-digit numbers.7.4: Multiply two-digit numbers.

Multiply. Show your work.Multiply. Show your work.

$ 25 x 38$ 25 x 38

$25X 38 200 750$950

7.5: Decide whether the answer to 7.5: Decide whether the answer to a problem is reasonable.a problem is reasonable.

Solve. Show your work.Solve. Show your work.

Use pictures, numbers, or words to Use pictures, numbers, or words to show that your answer is reasonable.show that your answer is reasonable.

Mrs. Dondlinger eats 32 Mrs. Dondlinger eats 32 Powerberries eachPowerberries each

day. How many Powerberries wouldday. How many Powerberries would

she eat in 14 days?she eat in 14 days?448 I took 32 and multiplied it by 14.

7.5: Decide whether the answer to 7.5: Decide whether the answer to a problem is reasonable.a problem is reasonable.

Solve. Show your work.Solve. Show your work.

Use pictures, numbers, or words to show that your Use pictures, numbers, or words to show that your answer is reasonable.answer is reasonable.

Mrs. Meyers, Mr. Thiemann, Mrs. Anderson and Mrs. Mrs. Meyers, Mr. Thiemann, Mrs. Anderson and Mrs. Dondlinger ran a relay race. Mrs. Meyers ran 125 Dondlinger ran a relay race. Mrs. Meyers ran 125 meters, Mr Thiemann ran 93 meters, Mrs. meters, Mr Thiemann ran 93 meters, Mrs. Anderson ran 234 meters, and Mrs. Dondlinger Anderson ran 234 meters, and Mrs. Dondlinger 145 meters. How many meters did they run 145 meters. How many meters did they run altogether?altogether?

125 + 93 + 234 + 145 = 597