TT7 Week 3

Week 3
Chapter 2
Lessons 9-14

Week 3: Chapter 2: Lessons 9-14

Key concepts

1. Commutative property of multiplication

2. Multiplying with 0

3. Long Multiplication

4. 2-digit multiplication

5. 3-digit multiplication

6. All in your head!

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Any 2 or more integers may be multiplied together in any order to obtain the same product.

​

​Commutative property of multiplication

Multiple Select

Rewrite 2+2+2+2+2+2+2 as a multiplication problem. Select all that apply

• 2x7

• 2x2

• 7x2

• 7x7

Multiple Choice

True or false. Multiplication is a way to write the same number added to itself over and over.

• true

• false

Mathematical rule:

Any number times 0 is equal to 0.

This is also called the Zero Property of Multiplicaiton

​

Multiplying with zeros

Math Response

What is the product?

$$597\times0$$

Type answer here

Correct Answer: 0

Deg^°

Rad

Math Response

If A x 1 = A

What is the product of

5756 x 1 = ?

Type answer here

Correct Answer: 5756

Deg^°

Rad

2 or more digit numbers with 0

​Example: 700x4

1. multiply the non-zero numbers (7 x 4 = 28)

2. add up the zeros (2)

3. Put the zeros on the end

   700 x 4 =2800

Math Response

What is the product of $$50\times70$$ ?

Type answer here

Correct Answer: 3500

Deg^°

Rad

Match

Match the following

• 400 x 60

• 349 x 0

• 2000 x 5000

• 4 x 1

• 60 x 9

24,000

0

10,000,000

4

540

• 24,000

• 0

• 10,000,000

• 4

• 540

Long multiplication is a way to multiply numbers larger than ten

​

​Long multiplication

52
x 6

Mark sells video games. He sells 6 games every week. How many does he sell in a year? (Hint: there are 52 weeks in a year)

Example problem

​1. Write it out.

2. Multiply the 1s values. Carry any numbers that are greater than 10!

3. multiply the tens on top by the ones on bottom. Add the carried 10s

52
x 6
2

52
x 6
312

​1

Match

Practice

• 73 x 2

• 826 x 3

• 5143 x 3

• 7469 x 5

146

2478

15429

37345

• 146

• 2478

• 15429

• 37345

But wait...What about 2-digit numbers?

Multiplying 2 numbers where each is 2 or more digits is a little tricky, but there are rules to follow to make it easier.

What is the next step?

​

Look at this example

What is the next step?
If you said multiply the 5 on top by the 2 in the ones column below, you'd be correct.
What's next?

​

Look at this example

What is the next step?
Multiply the 7 in the hundreds position up top by the 2 in the ones position below.

What's next?

​

Look at this example

Next, we put a zero in the ones position below the first product.

Then we repeat the process we just did, except we multiply the top numbers by the 3 in the bottom number

​

Look at this example

Next, we put a zero in the ones position below the first product.

Then we repeat the process we just did, except we multiply the top numbers by the 3 in the bottom number

​

Look at this example

Finally, we find the sum of the two products. This means we add them up!

1512 + 22680 = 24192

​

Look at this example

Math Response

Find the product:

$$64\times35$$

Type answer here

Correct Answer: 2240

Deg^°

Rad

Draw

What is the product of 956 x 94? Show your work. You can also write it on paper or a whiteboard and show me.

Another way...

Lets try something slightly different.

325 x 12

Step 1: Write it out linearly (side-by-side)

Step 2: Split the smaller number into 10s and 1s

Step 3:
Multiply the larger number by the 10s number.
(325 x 10 in this example)

Step 4:
Multiply the larger number by the 1s number.
(325 x 2 in this example)

Step 5:
Add up the two products.

Either method will work. Just use the one you find faster.

Remember, you can go to https://www.mathsisfun.com/numbers/multiplication-long.html

to check your work.

This method will work for any length of number! You just add steps to account for 100s or 1000s and split out the smaller number accordingly.

Math Response

Find the product:

$$5186\times34$$

Use whichever method works for you!

Type answer here

Correct Answer: 176324

Deg^°

Rad

Multiplying in your head is a matter of practice and memorization.

​

Mental Math!

There are some steps you can do

• For 2-digit numbers multiplied by single digit numbers, break the two digit number into tens and ones. Then multiply each by the single digit number. Eg. (27 x 3) Break the 27 into 20 and 7. Multiply 20x3 and 7x3, then add the products.

There are some steps you can do

• For larger numbers, you can sometimes do them partially in your head. If one of the numbers has zeros at the end, you can ignore the zeros until the end and then follow the normal mental math process. Eg. (723 x 2000) ignore the zeros in 2000. So now you just multiply 723 x 2. Then add the zeros back in at the end.

Poll

How do you feel about this week's lesson?

• Totally got this!

• I have a few questions still

• AAAHHHH!

Homework:

Ch 2 Lessons 9-14. upload your screenshot to Canvas!

Optional Canvas Quiz on Rational Numbers (you don't have to do this unless you want to)