Learn on PengiEureka Math, Grade 5Chapter 11: Mental Strategies for Multi-Digit Whole Number Division

Lesson 2: Use basic facts to approximate quotients with two-digit divisors.

In this Grade 5 Eureka Math lesson from Chapter 11, students learn how to approximate quotients with two-digit divisors by rounding the divisor to the nearest ten and adjusting the dividend to the nearest compatible multiple. Using mental math strategies, students break division problems like 402 ÷ 19 into simpler steps — for example, estimating as 400 ÷ 20 — to find reasonable estimated quotients. The lesson builds on prior fluency with dividing by multiples of 10 and rounding skills to support efficient mental computation.

Section 1

Finding Compatible Numbers

Property

To set up a division problem for estimation, change the original problem a÷ba \div b into an approximate problem a÷ba' \div b'.
First, round the divisor bb to the nearest ten to get bb'.
Then, find a compatible number aa' by choosing a multiple of bb' that is close to the original dividend aa.

Examples

Book overview

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Chapter 11: Mental Strategies for Multi-Digit Whole Number Division

  1. Lesson 1

    Lesson 1: Use divide by 10 patterns for multi-digit whole number division.

  2. Lesson 2Current

    Lesson 2: Use basic facts to approximate quotients with two-digit divisors.

  3. Lesson 3

    Lesson 3: Use basic facts to approximate quotients with two-digit divisors.

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Finding Compatible Numbers

Property

To set up a division problem for estimation, change the original problem a÷ba \div b into an approximate problem a÷ba' \div b'.
First, round the divisor bb to the nearest ten to get bb'.
Then, find a compatible number aa' by choosing a multiple of bb' that is close to the original dividend aa.

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 11: Mental Strategies for Multi-Digit Whole Number Division

  1. Lesson 1

    Lesson 1: Use divide by 10 patterns for multi-digit whole number division.

  2. Lesson 2Current

    Lesson 2: Use basic facts to approximate quotients with two-digit divisors.

  3. Lesson 3

    Lesson 3: Use basic facts to approximate quotients with two-digit divisors.