Grade 4 students learn to transition from using four partial products to the more efficient standard algorithm for two-digit by two-digit multiplication, using examples like 22 × 42 and 29 × 62. The lesson connects area models and the distributive property to the vertical algorithm, helping students see how two partial products align with place value. This lesson is part of Chapter 16 in Eureka Math, Grade 4.
Section 1
Area Model with Two Partial Products
To multiply a two-digit number by another two-digit number, you can decompose one factor into its tens and ones. The total product is the sum of the two resulting partial products. This can be represented by an area model split into two sections. For a problem , where is composed of (tens) and (ones), the property is:
Section 2
Multiplying 2-Digit Numbers Using the Standard Algorithm
To multiply two-digit numbers, calculate two partial products.
The first is the top number multiplied by the ones digit of the bottom number.
The second is the top number multiplied by the tens digit of the bottom number, with a zero placed in the ones place to account for place value.
The final product is the sum of these two partial products.
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Section 1
Area Model with Two Partial Products
To multiply a two-digit number by another two-digit number, you can decompose one factor into its tens and ones. The total product is the sum of the two resulting partial products. This can be represented by an area model split into two sections. For a problem , where is composed of (tens) and (ones), the property is:
Section 2
Multiplying 2-Digit Numbers Using the Standard Algorithm
To multiply two-digit numbers, calculate two partial products.
The first is the top number multiplied by the ones digit of the bottom number.
The second is the top number multiplied by the tens digit of the bottom number, with a zero placed in the ones place to account for place value.
The final product is the sum of these two partial products.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter