Grade 5 students learn to relate decimal multiplication to fraction multiplication using Eureka Math's approach of converting decimals to fractions with denominators of 10, 100, and 1,000. In this lesson, students rewrite expressions like 3.2 × 2.1 as 32/10 × 21/10, multiply numerators and denominators, and interpret the resulting unit (such as hundredths or thousandths) to find the decimal product. Students also practice estimation strategies to check the reasonableness of their answers before solving.
Section 1
Multiply Decimals by Converting to Fractions
To multiply decimals, you can convert each decimal to its equivalent fraction. Then, multiply the fractions by multiplying the numerators and the denominators. The resulting fraction can be converted back to a decimal to find the product.
Section 2
Standard Algorithm for Decimal Multiplication
To multiply decimals, first multiply the numbers as if they are whole numbers. The number of decimal places in the product is the sum of the number of decimal places in the factors.
Expand to review the lesson summary and core properties.
Section 1
Multiply Decimals by Converting to Fractions
To multiply decimals, you can convert each decimal to its equivalent fraction. Then, multiply the fractions by multiplying the numerators and the denominators. The resulting fraction can be converted back to a decimal to find the product.
Section 2
Standard Algorithm for Decimal Multiplication
To multiply decimals, first multiply the numbers as if they are whole numbers. The number of decimal places in the product is the sum of the number of decimal places in the factors.