Learn on PengienVision, Mathematics, Grade 4Chapter 5: Use Strategies and Properties to Divide by 1-Digit Numbers

Lesson 2: Mental Math: Estimate Quotients

In this Grade 4 enVision Mathematics lesson from Chapter 5, students learn how to estimate quotients using compatible numbers and multiplication when dividing 3-digit dividends by 1-digit numbers. Students practice replacing difficult numbers with nearby compatible numbers to make mental math easier, such as replacing 700 ÷ 9 with 720 ÷ 9 because 720 is divisible by 9. The lesson builds number sense by applying basic multiplication facts to check whether estimated quotients are reasonable in real-world contexts.

Section 1

Relating Division to Finding a Missing Factor

Property

Solving a division problem, such as A÷B=?A \div B = ?, is the same as finding the unknown factor in the related multiplication equation, B×?=AB \times ? = A.
The quotient of the division is the unknown factor.

Examples

Section 2

Choosing Compatible Numbers for Estimation

Property

Compatible numbers are numbers that are easy to compute mentally. When estimating quotients, replace the dividend with a nearby number that is a multiple of the divisor, which is often more effective than using standard rounding rules.

Examples

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Relating Division to Finding a Missing Factor

Property

Solving a division problem, such as A÷B=?A \div B = ?, is the same as finding the unknown factor in the related multiplication equation, B×?=AB \times ? = A.
The quotient of the division is the unknown factor.

Examples

Section 2

Choosing Compatible Numbers for Estimation

Property

Compatible numbers are numbers that are easy to compute mentally. When estimating quotients, replace the dividend with a nearby number that is a multiple of the divisor, which is often more effective than using standard rounding rules.

Examples