Chapter 2 · Multiplying and dividing by two-digit numbers

Lesson 2.4 · Multiplying a two-digit number by a two-digit number (1)

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 31–33).

Grade 3 Second Semester Pages 31–33 ECNU Press

Lesson Alignment

How this Shanghai Maths lesson connects to learning goals, Common Core, and Eureka Math.

Learning Objectives

Students will be able to:

  1. 01Calculate two-digit × two-digit using multiple methods. (Question 1)
  2. 02Use splitting ($48\times25 = 48\times20 + 48\times5$). (Question 2)
  3. 03Work mentally with $\times 10$ and $\times 100$ patterns. (Question 3)

Common Core Standards

CodeStandard (focus for this lesson)
4.NBT.B.5Multiply two two-digit numbers using strategies.
3.OA.B.5Distributive property.

Eureka Math Correspondence

Shanghai MathsFocusEureka Math
MethodsSplit / columnG4 M3 preview
Mental×10 patternsG3 M3

Core Concepts

Introduce two-digit × two-digit: mental $10\times$, split, column.

Methods

Same product: column, split, or regroup ($5\times24 + 20\times24$).

Split

$48 \times 25 = 48 \times (20 + 5)$ using distributive property.

Mental ×10

$16 \times 10$, $24 \times 10$, $12 \times 100$ — shift place value.

Key Terms & Definitions (Reference)

Quick glossary for this lesson.

TermDefinition
Two-digit × two-digitBoth factors are 10–99.
Distributive propertySplit one factor to multiply in parts.

Key Answers

Quick reference for this lesson’s exercise answers.

1. Mental / boxes

  • $16\times10=160$,\; $16\times5=80$,\; sum $240$;\; $16\times10+16\times15=16\times25$
  • $24\times10=240$,\; $24\times5=120$,\; sum $360$;\; $24\times10+24\times5=24\times15$
  • $33\times10=330$,\; $33\times5=165$,\; sum $495$;\; $33\times10+33\times5=33\times15$

2. Estimate then calculate

  1. $73\times42=3066$
  2. $29\times67=1943$

3. Different methods for $48\times25$

All give $1200$

4. Calculate

  • $19\times27=513$;\; $43\times77=3311$;\; $31\times19=589$

5. Number sentences

  1. $550-19\times19=189$
  2. $99\times100=9900$

6. Application

  1. $160$ balls
  2. Grandpa $72$ years old
  3. Yes — cost $11200$ yuan ($<12000$)

7. Enhancement

$142857\times3=428571$: $A=4$,\; $B=2$,\; $C=8$,\; $D=5$,\; $E=7$