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

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 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

4-1 MENTAL MATH I can… multiply by multiples of 10 Example: Find 30 x 80 Steps: Find the basic fact 3 x 8 =24 1. Another way: Find 30 x 80 Count the zeros in the original problem (2) 2. 1. Think of 30 x 80 as …. 3 x 10 x 8 x 10 3. Add the zeros to the product of the basic fact 2. Regroup the factors like this: 2,400 (3 x 8) x (10 x 10) 3. Multiply 24 x 100 = 2,400

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: 10 4 20 200 80 200 + 80 = 280

4-3 Estimate: Use Rounding I can… estimate products by rounding the factors How to Show Your Work: Example: Estimate 28 x 36 28 x 36 = n 30 x 40 = 1,200 So, the product of 28 and 36 is about 1,200.

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: 25 and 4 are compatible numbers, 27 x 4 27 x 4 ★ and easy to multiply Using compatible numbers can get ★ 30 x 4 = 120 25 x 4 = 100 you a CLOSER estimate (27 is closer to 25 than 30)

4-5 Arrays and Partial Products I can… arrays, place value, and partial products to help multiply Example: Find 12 x 24

4-6 Using Partial Products to Multiply I can… use are models and properties of operations to multiply

4-7 Use Partial Products to Multiply 2 digit Numbers I can… use place value and partial products to multiply Example 2: Example 1: 2 7 3 x 9 = 27 3 0 3 x 10 = 30 9 0 10 x 9 = 90 10 x 10 = 100 1 0 0 + _______ 2 4 7

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!