In this Grade 5 Eureka Math lesson from Chapter 9, students practice multiplying whole numbers by decimals with hundredths, using place value understanding and estimation to reason about products. Students apply area models and the standard algorithm to solve problems such as 2.31 × 22 and 0.98 × 495, building fluency with multi-digit decimal multiplication. The lesson consolidates learning from earlier lessons in the module and extends to decimals less than 1 as a challenge for advanced learners.
Section 1
Multiply a Whole Number by a Decimal to the Hundredths Place
To multiply a whole number by a decimal with hundredths, first multiply the numbers as if they were both whole numbers. Because the decimal factor is 100 times smaller than its whole number form (e.g., is 100 times smaller than ), the product must be adjusted by dividing by 100. This is equivalent to placing the decimal point two places from the right in the final product.
Section 2
Solving Multi-Step Word Problems with Decimal Multiplication
Solving multi-step problems involves a sequence of operations. A common pattern is to first find the product of a whole number and a decimal, and then use that product in a second calculation.
Expand to review the lesson summary and core properties.
Section 1
Multiply a Whole Number by a Decimal to the Hundredths Place
To multiply a whole number by a decimal with hundredths, first multiply the numbers as if they were both whole numbers. Because the decimal factor is 100 times smaller than its whole number form (e.g., is 100 times smaller than ), the product must be adjusted by dividing by 100. This is equivalent to placing the decimal point two places from the right in the final product.
Section 2
Solving Multi-Step Word Problems with Decimal Multiplication
Solving multi-step problems involves a sequence of operations. A common pattern is to first find the product of a whole number and a decimal, and then use that product in a second calculation.