Chapter 2 · Multiplying and dividing by two-digit numbers

Lesson 2.3 · Multiplying whole tens by a two-digit number

Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 28–30).

Grade 3 Second Semester Pages 28–30 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 whole tens × two-digit using reasoning. (Question 1)
  2. 02Write number sentences for sum-of-groups problems. (Question 2)
  3. 03Solve packing / cost problems with two methods. (Question 3–4)

Common Core Standards

CodeStandard (focus for this lesson)
3.NBT.A.3Multiply one-digit by multiples of 10.
4.NBT.B.5Multiply using place-value strategies (preview).

Eureka Math Correspondence

Shanghai MathsFocusEureka Math
Q1Tens languageG3 M3
Q2–3Number sentencesG3 M3 application

Core Concepts

Use place value: $30 \times 24 = 3\ tens \times 24$.

Tens Pattern

$40 \times 23 = 4 \times 23 \times 10 = 920$ — multiply, then attach zero.

Number Sentences

“Sum of 23 four hundreds” → $400 \times 23$.

Two Methods

Pack cost: $24 \times 15$ jiao — split or column; compare answers.

Key Terms & Definitions (Reference)

Quick glossary for this lesson.

TermDefinition
Whole tensA multiple of 10.
ProductResult of multiplication.

Key Answers

Quick reference for this lesson’s exercise answers.

1. Calculate with reasoning

  • $4\times12=48$,\; $40\times12=480$,\; $400\times12=4800$
  • $45\times7=315$,\; $450\times7=3150$,\; $4500\times7=31500$

2. Mental calculation

  • $63\times60=3780$,\; $42\times30=1260$,\; $6\times1500=9000$,\; $13\times500=6500$,\; $200\times400=80000$
  • $100\times30=3000$,\; $50\times18=900$,\; $2\times50=100$,\; $8\times400=3200$,\; $20\times4000=80000$
  • $4\times250=1000$,\; $75\times30=2250$,\; $88\times30=2640$,\; $6\times110=660$,\; $28\times60=1680$
  • $17\times20=340$,\; $160\times9=1440$,\; $700\times17=11900$,\; $5400\times6=32400$,\; $800\times44=35200$

3. Compare without calculating

  • $250\times40=40\times250$;\; $1300\times4=13\times400$;\; $6500\times330>650\times330$;\; $47\times210<470\times210$

4. Think carefully

  1. $34\times6=204$ via $180+24$
  2. $52\times7=364$ via $350+14$

5. Calculate smartly

  • $656\times62-56\times62=37200$
  • $2\times98+98\times98=9800$
  • $101\times101-101=10100$

6. Number sentences

  1. $400\times23=9200$
  2. $(18+87)\times500=52500$

7. Application

  1. $18900\,\text{m}$
  2. $240$ yuan; $90$ yuan; $20$ pencilboxes cost more
  3. Total $768$ jiao (methods: $360+408$ or $32\times24$)

8–9. Enhancement

  1. $a=19$
  2. $5\times50=250$;\; $6\times60=360$;\; $9\times50=450$