Lesson: Estimating the Product of Two Decimals Mathematics • 5th Grade

In this lesson, we will learn how to use rounding and compatible numbers to estimate the product of two decimal numbers.

Lesson Plan

Students will be able to

estimate the product of a pair of decimals between 0 and 100 with up to two decimal places by rounding one or both to the nearest whole number or 10,
estimate the product of a pair of decimals between 0 and 100 with up to two decimal places using compatible numbers,
use estimation to check the reasonableness of a decimal multiplication.

Lesson Worksheet

Q1:

Which of the following is the nearest to upon rounding one of the two numbers to either 10, 100, or 1,000?

Q2:

Elizabeth wants to buy a pair of jeans that cost $49 .99. The sign on the display says that the jeans are off. Which expression can be used to best estimate the discount?

Q3:

Which of the following is closest to the result of after rounding one of the two numbers to 10, 100, or 1,000?