Topic 4 Multiples of 10 4-3: Estimate: Use Rounding Use Strategies - - PowerPoint PPT Presentation

▶

Oct 22, 2022 563 likes •662 views

4-1: Mental Math: Multiply Multiples of 10 4-2: Use Models to Multiply 2-Digit Numbers by Topic 4 Multiples of 10 4-3: Estimate: Use Rounding Use Strategies and Properties to 4-4: Estimate: Use Compatible Numbers Multiply by 2-Digit Numbers

SLIDE 1

Topic 4

4-1: Mental Math: Multiply Multiples of 10 4-2: Use Models to Multiply 2-Digit Numbers by Multiples of 10 4-3: Estimate: Use Rounding 4-4: Estimate: Use Compatible Numbers 4-5: Arrays and Partial Products 4-6: Multiply Using the Distributive Property 4-7: Use Partial Products to Multiply by 2-Digit Numbers 4-8: Multiply 2-Digit Numbers by Multiples of 10

Use Strategies and Properties to Multiply by 2-Digit Numbers

SLIDE 2

4-1 MENTAL MATH

I can… multiply by multiples of 10

Example: Find 30 x 80 Steps: 1. Find the basic fact 3 x 8 =24 2. Count the zeros in the original problem (2) 3. Add the zeros to the product of the basic fact

2,400

Another way: Find 30 x 80 1. Think of 30 x 80 as …. 3 x 10 x 8 x 10 2. Regroup the factors like this: (3 x 8) x (10 x 10)

3. Multiply 24 x 100

= 2,400

SLIDE 3

4-2 Use Models to Multiply 2-Digit Numbers by Multiples of 10 I can… use models and properties of operations to help me multiply

How to show your work (without graph paper) for 20 x 14:

20 10 4 200 80 200 + 80 = 280

SLIDE 4

4-3 Estimate: Use Rounding

I can… estimate products by rounding the factors

How to Show Your Work:

28 x 36 = n 30 x 40 = 1,200 So, the product of 28 and 36 is about 1,200.

Example:

Estimate 28 x 36

SLIDE 5

4-4 Estimate: Use Compatible Numbers

I can… use compatible numbers to estimate Compatible numbers: numbers that are easy to compute mentally Example: Estimate 27 x 4 Using rounding: Using Compatible Numbers: 27 x 4 27 x 4 30 x 4 = 120 25 x 4 = 100

★ 25 and 4 are compatible numbers, and easy to multiply ★ Using compatible numbers can get you a CLOSER estimate (27 is closer to 25 than 30)

SLIDE 6

4-5 Arrays and Partial Products

I can… arrays, place value, and partial products to help multiply Example: Find 12 x 24

SLIDE 7

4-6 Using Partial Products to Multiply

I can… use are models and properties of operations to multiply

SLIDE 8

4-7 Use Partial Products to Multiply 2 digit Numbers

I can… use place value and partial products to multiply Example 1:

3 x 9 = 27 3 x 10 = 30 10 x 9 = 90 10 x 10 = 100

2 7 3 0 9 0 1 0 0 + _______ 2 4 7 Example 2:

SLIDE 9

4-8 Multiply 2-Digit Numbers by Multiples of 10

I can… use area models and place value strategies to multiply by multiples of 10

Think: this is the same as multiply 2 x 28, and adding a zero!