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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 14 minutes
0 of 16 done
Part 1 of 8Picture It

Step 1: Picture It

Start with something you already know.

One road, both ways

  1. You walk the road from your house to the park.
  2. To walk home, you do not need a new road.
  3. You use the same road, the other way.

Division uses the times tables you know, read the other way.

18 ÷ 3 asks: 3 times what makes 18?

Step 2: Let's Learn

Read it, or press Listen and follow the words.

Try it first

Noor plants 20 carrots in rows of 4. How many rows does she plant?

rows

Stuck is fine. Let’s Learn shows the way next. Got it first time? You can jump ahead to Watch an Example.

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 3: 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 4: 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. People who use numbers all day divide this way.

Step 5: Watch an Example

One step at a time.

Watch Ana Turn a Division Round

Ana needs to find 35 ÷ 5.

  1. Step 1

    Ana thinks of 35 balls in rows of 5. How many rows?

Watch Leo Turn a Division Round

Leo needs to find 10 ÷ 2. He starts, and you finish.

  1. Step 1

    Leo turns it round: what times 2 makes 10? So ☐ × 2 = 10.

Step 6: Your Turn

Practice makes it stick.

The Ticket Booth

Problem 1 of 12

Tickets cost $3 each. Sam pays $30 in all. How many tickets does he buy?

tickets

The Egg Tray

Problem 2 of 12

A tray holds 50 eggs in rows of 10. How many rows does it have?

rows

Find the Missing Factor

Turn each one into a multiplication with a gap.

Problem 3 of 12

☐ × 10 = 60. What number fills the gap?

Problem 4 of 12

16 ÷ 2 = ?

Problem 5 of 12

A box holds 30 stars in rows of 6. Which number sentence finds the rows?

6 in each row30 stars in all? rows

Find the Mistake

One line on each page is a slip. Find it, then fix it.

Problem 6 of 12

Dev finds 25 ÷ 5. One line is a slip. Which?

Dev's answer for 25 ÷ 5

  1. 125 ÷ 5 = ☐
  2. 24 × 5 = 25
  3. Answer25 ÷ 5 = 4

Problem 7 of 12

What should Dev's quotient be?

Problem 8 of 12

Maya finds 20 ÷ 5. One line is a slip. Which?

Maya's answer for 20 ÷ 5

  1. 120 ÷ 5 = ☐
  2. 220 × 5 = ☐
  3. Answer20 ÷ 5 = 100

Problem 9 of 12

What should Maya's quotient be?

Which Way?

Pick the way that fits.

Problem 10 of 12

Noor must find 24 ÷ 3. Which fact helps?

Problem 11 of 12

Ravi says 9 ÷ 3 = 3. Which way checks it?

Build the Rows

Build it, then read the division underneath.

Problem 12 of 12

Build 8 blocks in rows of 2. How many rows does it take?

Set 2 in each row, then add rows until you reach 8.

1 = 1

1 × 1 = 1

1 ÷ 1 = 1

1 row of 1 makes 1.

Step 7: Quick Check

Show what you know.

Question 1 of 2

45 ÷ 5 = ?

Question 2 of 2

What question does 24 ÷ 6 really ask?

Ready for more?Optional. Past the lesson, for anyone who wants it.

Stretch 1 of 2

Priya's division has the answer 7. Which one is it?

Stretch 2 of 2

☐ ÷ 10 = 9. What number fills the gap?

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.

The slip this lesson targets is reading ÷ as "multiply these two numbers": 20 ÷ 5 becomes 20 × 5. Ask "what times 5 makes 20?" and have them say the gap out loud before they write anything. The other slip is a miscount while skip-counting, as in Dev's 4 × 5 = 25; the cure is the check, because 4 × 5 gives 20 back and not 25. When the check does not give the starting number back, the answer is not finished.

Division is a multiplication with a gap — 12 ÷ 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 much — Most 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 zero — 12 ÷ 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 instead — 12 ÷ 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.