Chapter 7, Lesson 3Multiplying Ones, Tens, and Hundreds with Regrouping

What types of problems have we solved so far?

9 x 8

90 x 8

80 x 9

900 x 8

Strategies we have worked on . . .

Making ten and subtract a group

If I know 4’s I can double to make 8’s

Multiplying by ten . . .

Multiplying by one hundred . . .

What types of problems have we solved so far?23 x 4 Distributive

PropertyCompose and

decompose into place values

Partial Products – begin in either ones or greatest place value on the left

Use doubling and halving

1. Multiply Ones, Tens, and Hundreds with Regrouping

What is regrouping? Can you give me an example with addition?

15 x 5

4 x 31

Compare to the bookBreaking or decomposing into place

valuesWork with the place value – 3 x 30 is

not the same as 3 x 3. We call the 30 – 3 tens or thirty.

We can write the whole value of the multiplication problem and then add up all the products.

Shortcut can be writing the digits in the right place value showing the regrouping above the place value.

Grade 3Chapter 9 – Lesson 1 – Real-World Problems: Multiplication

Use bar models to solve one-step multiplication word problems

Bar modelsWhat are unit bars? What do they

represent?How many units are in this

diagram?How many dots are there in each

unit?How many dots are there in all?How did you figure that out?

What do we do when we solve word problems?Read the problemWhat do I have to answer?Re-read each sentence and draw the bar

models, label the units. Adjust the bars as necessary. Place your question mark.

Check your diagram. Write the equations to solve the

problems, solve the problem Check your answer. (Plug value back into

the diagram. Check the arithmetic.)

There are 5 boxes of pencils.Each box contains 12 pencils.How many pencils are there in all?

Compare to our bookWhat do you see as the same?What do you see as different?What does “twice” mean? Can

you tell your partner a problem that uses the word twice?

Partners do you agree with how they used the word twice.

Zach has 342 stamps.Ron has twice as many stamps as Zach.How many stamps does Ron have?