Learn on PengienVision, Mathematics, Grade 4Chapter 3: Use Strategies and Properties to Multiply by 1-Digit Numbers

Lesson 2: Estimate Products

Property.

Section 1

Estimating Products Using Compatible Numbers

Property

To estimate a product $a \times b$ , replace the factors with nearby compatible numbers, $c$ and $d$ , such that $c \approx a$ and $d \approx b$ . The estimate is the product $c \times d$ .

Examples

Section 2

Estimating Products Using Rounding

Property

To estimate the product of two numbers, round one or both factors to a nearby place value (like the nearest ten or hundred) to make the multiplication easier to perform mentally. The symbol $\approx$ means "approximately equal to".

Examples

To estimate $48 \times 7$ , round $48$ to the nearest ten, which is $50$ . Then, calculate $50 \times 7 = 350$ . So, $48 \times 7 \approx 350$ .

To estimate $615 \times 4$ , round $615$ to the nearest hundred, which is $600$ . Then, calculate $600 \times 4 = 2400$ . So, $615 \times 4 \approx 2400$ .

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Estimating Products Using Compatible Numbers

Property

To estimate a product $a \times b$ , replace the factors with nearby compatible numbers, $c$ and $d$ , such that $c \approx a$ and $d \approx b$ . The estimate is the product $c \times d$ .

Examples

Section 2

Estimating Products Using Rounding

Property

Examples

To estimate $48 \times 7$ , round $48$ to the nearest ten, which is $50$ . Then, calculate $50 \times 7 = 350$ . So, $48 \times 7 \approx 350$ .

To estimate $615 \times 4$ , round $615$ to the nearest hundred, which is $600$ . Then, calculate $600 \times 4 = 2400$ . So, $615 \times 4 \approx 2400$ .

Overview

Lesson overview

Review the lesson summary and core properties without leaving the current page.

Overview

Section 1

Estimating Products Using Compatible Numbers

Property

To estimate a product $a \times b$ , replace the factors with nearby compatible numbers, $c$ and $d$ , such that $c \approx a$ and $d \approx b$ . The estimate is the product $c \times d$ .

Examples

Section 2

Estimating Products Using Rounding

Property

Examples

To estimate $48 \times 7$ , round $48$ to the nearest ten, which is $50$ . Then, calculate $50 \times 7 = 350$ . So, $48 \times 7 \approx 350$ .

To estimate $615 \times 4$ , round $615$ to the nearest hundred, which is $600$ . Then, calculate $600 \times 4 = 2400$ . So, $615 \times 4 \approx 2400$ .