Whole Number and Decimal Multiplication

Big Ideas

Represent multiplication of whole numbers and decimals to the hundredths with objects/pictorial models, including area models

Multiply a three-digit by a two-digit whole number

Multiply decimals to the hundredths

Multiplication of Whole Numbers

• Have your student estimate about how much his or her purchase will cost. He or she may round to whole numbers or use compatible numbers to help estimate. For example, 4 × 2.89 is close to 4 × 3, and 4 × 3 = 12. The total cost will be about $12. Similarly, a product can be estimated if one of the numbers has two digits. So, 16 × $3.18 is close to 15 × 3, and 15 × 3 = 45. The total cost is about $45.
• Practice using partial products while doing multiplication. This can be a two-person activity with you and your child. Use easier three-digit numbers. For example, try 300 × 120. Tell your child, “You figure out 300 × 100, and I’ll figure out 300 × 20. Then we can add those two numbers together to get the result.” (300 × 100 = 30,000; 300 × 20 = 6,000; 30,000 + 6,000 = 36,000)

Multiplication of Decimals