In this Grade 5 enVision Mathematics lesson from Chapter 4, students learn how to estimate the product of a decimal and a whole number using two key strategies: rounding and compatible numbers. The lesson covers how to apply these techniques to decimals less than one as well as decimals greater than one, and how to determine whether an estimate is an overestimate or an underestimate. Students practice both strategies across a variety of real-world contexts, such as calculating costs and distances.
Section 1
Confirming Decimal Placement with Estimation
To estimate the product of a decimal and a whole number, round the decimal to the nearest whole number and multiply. The actual product will be approximately equal to the estimated product, which helps confirm the correct placement of the decimal point.
Section 2
Estimate Decimal Products Using Compatible Numbers
To estimate a product using compatible numbers, replace the factors with numbers that are close to the original values and are easy to multiply mentally. The product of the compatible numbers is the estimate.
Expand to review the lesson summary and core properties.
Section 1
Confirming Decimal Placement with Estimation
To estimate the product of a decimal and a whole number, round the decimal to the nearest whole number and multiply. The actual product will be approximately equal to the estimated product, which helps confirm the correct placement of the decimal point.
Section 2
Estimate Decimal Products Using Compatible Numbers
To estimate a product using compatible numbers, replace the factors with numbers that are close to the original values and are easy to multiply mentally. The product of the compatible numbers is the estimate.