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Math · Grade 3 Math

Chapter 1: Multiplication and Division as Equal Groups

Division as an Unknown Factor

Every division is a multiplication with a gap in it.

Lesson
4
Time
About 13 minutes
0 of 9 done
Part 1 of 7Let's Learn

Step 1: Let's Learn

Read it, or press Listen and follow the words.

Watch the idea first — 57 seconds. Then read on, and try it yourself in the next step.

56 ÷ 8 asks a question you can answer with multiplication: what times 8 makes 56?

You have done this before

Earlier, subtraction was finding a missing part. Division is finding a missing factor.

No second table

If you know your times tables, you already know your division facts. They are the same facts.

Check by multiplying

If 24 ÷ 6 = 4, then 4 × 6 should give 24 back.

Step 2: Try It Yourself

One relationship, read four ways.

The array shows the multiplication and the division at the same time.

6 + 6 + 6 + 6 = 24

4 × 6 = 24

24 ÷ 4 = 624 ÷ 6 = 4

4 rows of 6 makes 24.

The same total, laid out every way it goes. What will not fit sits outside.

4 × 6 = 24. 4 and 6 are a factor pair of 24.

Pairs you have found

  • 4 × 6

Step 3: In Real Life

In a bakery

A baker needs 56 rolls and a tray holds 8. She does not divide. She asks: 8 times what makes 56? Seven trays. Asking for the missing factor is how people who use numbers all day actually divide.

Step 4: Watch an Example

One step at a time.

Watch Leo Turn a Division Round

Leo is asked for 35 ÷ 5.

  1. Step 1

    He rewrites it as a question about multiplication: what times 5 makes 35?

Step 5: Your Turn

Practice makes it stick.

The Seating Plan

Problem 1 of 2

30 chairs are put into rows of 5. How many rows are there?

rows

Checking Work

Problem 2 of 2

Ana says 28 ÷ 4 = 7. Check it: what is 7 × 4?

Find the Missing Factor

1 of 4

? × 5 = 20. What is the missing factor?

2 of 4

18 ÷ 2 = ?

3 of 4

40 ÷ 10 = ?

4 of 4

? × 3 = 15. What is the missing factor?

Build the Array

Build it, then check.

Build 4 rows of 6.

Set the rows and the columns.

1 = 1

1 row of 1 makes 1.

Step 6: Quick Check

Show what you know.

Question 1 of 2

45 ÷ 5 = ?

Question 2 of 2

What question does 24 ÷ 6 really ask?

What You Learned

  • A division asks for a missing factor.
  • 56 ÷ 8 means: what times 8 makes 56?
  • Your times tables are your division facts too.
For the grown-up

This lesson is where the child solves a division by finding the unknown factor in a related multiplication. Multiplication is equal groups before it is a fact to recall. Three fours is three groups of four, and division is the same picture asked from the other end.

Watch for multiplication and division being learned as separate subjects. They are one relationship, and a child who sees that halves what there is to remember.

When they are stuck on a division, ask the multiplication instead: "what times 4 gives 24?" Nearly every child can answer that when they cannot answer 24 divided by 4.

Division is a multiplication with a gap12 ÷ 3 asks: three times what makes 12? Written as a multiplication it is 3 × ? = 12. Any division can be rewritten this way, which means you never need a separate set of division facts — you need the times tables and the habit of reading them backwards.

Why this rewriting helps so muchMost children find recall of 3 × 4 = 12 easier than recall of 12 ÷ 3 = 4, simply because they practiced it more. Turning every division into a missing-factor question lets you use the stronger memory. This is not a trick for beginners — it is how the two operations actually relate.

You cannot divide by zero12 ÷ 0 would ask: zero times what makes 12? Nothing works, because zero times anything is zero. There is no answer, so the question is not allowed. Understanding it as a missing-factor question is what makes this rule sensible rather than arbitrary.

Ask the multiplication instead12 ÷ 3 = ☐ Turn it round: 3 × ☐ = 12 What times 3 makes 12? Four. So 12 ÷ 3 = 4 Every division you meet is a multiplication with a gap in it.