chapter 7, lesson 3 multiplying ones, tens, and hundreds with regrouping
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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?
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