In this Grade 5 Pengi Math lesson from Chapter 4, students learn how to estimate decimal products by rounding and using compatible numbers to simplify mental computation. They practice predicting the size of a product before calculating and then use estimation to verify correct decimal placement in their answers.
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.