3RD GRADE MATHEMATICS • OPERATIONS AND ALGEBRAIC THINKING

Multiply and Divide Within 100

Learn how multiplication and division are best friends — and use their relationship to solve problems quickly!

Where Did Multiplication Come From?

People have been multiplying for thousands of years! Long ago, farmers needed to count big groups of things, like sheep or bags of grain. Instead of counting one by one, they found faster ways. Let's look at some cool moments in the history of multiplication.

About 4,000 years ago
People in ancient Babylon (modern-day Iraq) carved multiplication tables into clay tablets. These are some of the oldest math "cheat sheets" ever found!
About 3,000 years ago
Ancient Egyptians used a method called "doubling" to multiply. They would double numbers over and over and add them up. It was clever, but slow!
About 2,300 years ago
In ancient China, people used counting rods — little sticks placed on a board — to multiply and divide. It was like an early calculator!
About 500 years ago
Mathematicians in India and the Middle East gave us the × symbol and the ÷ symbol. These are the same ones we use today!

All these people figured out the same thing you are learning right now: multiplication is just a fast way to add equal groups, and division is a fast way to split things into equal groups. You are part of a long history of math thinkers!

The Big Ideas

Before we start solving problems, let's learn four important ideas. These are the building blocks you'll use again and again.

1

Multiplication = Equal Groups

When you multiply, you are counting equal groups. For example, 4 × 3 means "4 groups of 3." That's 3 + 3 + 3 + 3 = 12.
2

Division = Sharing Equally

When you divide, you split a total into equal groups. For example, 12 ÷ 4 means "split 12 into 4 equal groups." Each group gets 3.
3

They Are Opposites!

Multiplication and division undo each other. If 6 × 7 = 42, then 42 ÷ 7 = 6. Knowing one helps you figure out the other.
4

Fact Families Stick Together

Three numbers that go together in multiplication and division make a fact family. The numbers 3, 5, and 15 make four facts: 3 × 5 = 15, 5 × 3 = 15, 15 ÷ 3 = 5, and 15 ÷ 5 = 3.
KEY TAKEAWAY
Think of multiplication and division like a zipper. Multiplication zips things together into one big number, and division unzips that big number back into smaller, equal pieces. If you know how to zip, you already know how to unzip!

See It: Arrays Show Both!

An array is a picture that shows objects in rows and columns. Arrays are amazing because they let you see multiplication AND division at the same time! Look at the array below. It shows 4 rows of 6 stars.

An array of 24 stars arranged in 4 rows and 6 columns, showing that 4 × 6 = 24 and 24 ÷ 4 = 6.

See how one picture gives you two facts? The array shows 4 × 6 = 24 (4 rows of 6). It also shows 24 ÷ 4 = 6 (24 stars split into 4 rows gives 6 in each row). You can even flip it: 6 × 4 = 24 and 24 ÷ 6 = 4. One array, four facts!

How It Works: The Relationship

Here's the biggest secret in 3rd-grade math: multiplication and division are connected. If you know one fact, you can figure out the other. Let's see how.

MULTIPLICATION
8 × 7 = 56
This means "8 groups of 7 equals 56."

Since 8 groups of 7 makes 56, we can "go backwards." If we start with 56 and make 8 equal groups, each group will have 7.

DIVISION (GOING BACKWARDS)
56 ÷ 8 = 7
Start with 56. Split into 8 groups. Each group has 7.

And we can also ask: if we start with 56 and put 7 in each group, how many groups do we get?

ANOTHER DIVISION FACT
56 ÷ 7 = 8
Start with 56. Put 7 in each group. You get 8 groups.

And don't forget — you can swap the order in multiplication! 7 × 8 = 56 is also true. This is called the commutative property, which is a big word that just means "you can swap the numbers and the answer is the same."

🌟 FUN FACT
Because you can swap numbers, learning 8 × 7 also teaches you 7 × 8 for free! That means every multiplication fact you memorize actually gives you four total facts (two multiplication, two division). You're four times smarter than you think!

Fact Families: Numbers That Belong Together

A fact family is a group of three numbers that are connected by multiplication and division. Every fact family makes exactly four math facts — two multiplication and two division. Let's look at one!

A fact family triangle showing the numbers 6, 9, and 54 with their four related multiplication and division facts.

The triangle shape helps you remember: the product (the big answer) goes at the top, and the two factors (the numbers you multiply) go at the bottom. To divide, start at the top and go down to find the missing factor!

Here's a table with more fact families. See if you can spot the pattern!

FactorsMultiply #1Multiply #2Divide #1Divide #2
3, 73 × 7 = 217 × 3 = 2121 ÷ 3 = 721 ÷ 7 = 3
5, 85 × 8 = 408 × 5 = 4040 ÷ 5 = 840 ÷ 8 = 5
6, 96 × 9 = 549 × 6 = 5454 ÷ 6 = 954 ÷ 9 = 6
8, 78 × 7 = 567 × 8 = 5656 ÷ 8 = 756 ÷ 7 = 8
9, 99 × 9 = 819 × 9 = 8181 ÷ 9 = 981 ÷ 9 = 9
🤔 DID YOU NOTICE?
When both factors are the same number (like 9 × 9), the fact family only has two unique facts instead of four. That's because swapping two equal numbers doesn't change anything!

Worked Example: Solve Step by Step

Let's solve a problem together. Read each step carefully!

Problem: Mia has 72 stickers. She wants to put them into 8 equal piles. How many stickers are in each pile?
1
Step 1 — What are we asked?We need to find how many stickers go in each pile when 72 stickers are shared equally into 8 piles. This is a division problem!
72 ÷ 8 = ?
2
Step 2 — Think of a multiplication factAsk yourself: "8 times what number equals 72?" Think about the 8 times table:
8 × 7 = 56… not enough. 8 × 8 = 64… still not 72. 8 × 9 = 72… Yes! That's it!
3
Step 3 — Write the answerSince 8 × 9 = 72, we know that 72 ÷ 8 = 9.
4
Step 4 — Check it!Does 9 × 8 really equal 72? Let's see: 9 × 8 = 72. ✅ It works!
Answer: Mia puts 9 stickers in each pile.
KEY TAKEAWAY
When you're stuck on a division problem, flip it around! Turn "72 ÷ 8 = ?" into "8 × ? = 72." It's like using a key that fits both locks — multiplication and division are the same key, just turned different ways.

Helpful Strategies

There's more than one way to multiply and divide! Here are some strategies that make these problems easier. Try them all and pick the ones you like best.

StrategyHow It WorksExample
Use a Fact FamilyTurn division into multiplication (or the other way around) to use what you already know.Don't know 42 ÷ 6? Think: 6 × ? = 42. Answer: 7!
Skip CountingCount by the same number over and over: 3, 6, 9, 12…For 4 × 3, count by 3 four times: 3, 6, 9, 12.
Break Apart (Distributive)Split a hard problem into two easy problems and add the answers.7 × 6 = (5 × 6) + (2 × 6) = 30 + 12 = 42
DoublesUse doubling for ×2, ×4, and ×8 facts.For 4 × 6, double 6 to get 12, then double 12 to get 24.
Use 10s and SubtractFor ×9, multiply by 10 and subtract one group.9 × 7 = (10 × 7) − 7 = 70 − 7 = 63

The break apart strategy is especially powerful. Let's look at it more closely. Say you need to find 8 × 7. That's a tough one! But you can break the 8 into 5 + 3:

BREAK APART STRATEGY
8 × 7 = (5 × 7) + (3 × 7) = 35 + 21 = 56
Split the 8 into 5 + 3, multiply each part by 7, then add!
KEY TAKEAWAY
Think of these strategies like tools in a toolbox. A carpenter doesn't use only a hammer — sometimes a screwdriver works better! When one strategy feels hard, switch to another. The more tools you have, the faster you can solve any problem.

What Comes Next?

Great news — everything you're learning now will help you with bigger math later! Here's a peek at what's ahead.

What You Know NowWhat You'll Learn Later
Multiply within 100 (like 8 × 7 = 56)Multiply bigger numbers (like 28 × 37) in 4th and 5th grade
Divide within 100 (like 56 ÷ 8 = 7)Long division with larger numbers and remainders
Fact families connect × and ÷Algebra! In 6th grade, you'll use letters like x and solve equations like 8 × x = 56
Break apart strategyThe distributive property — a rule used all through high school math!

By memorizing your multiplication and division facts now, you're building a strong math foundation. It's like learning to read — once you know words well, you can read whole books! Once you know these facts well, you can do any math problem that comes your way.

🚀 LOOK AHEAD
In 4th grade, you'll learn about factors and multiples. Guess what — you're already using them! When you say 6 × 9 = 54, the numbers 6 and 9 are factors of 54, and 54 is a multiple of both 6 and 9. You're already ahead!

Practice Problems

Time to try some on your own! Start with the easier ones and work your way up. Click "Show Answer" when you're ready to check.

PROBLEM 1WHAT DO YOU KNOW?
If you know that 6 × 8 = 48, what are the other three facts in this fact family?
PROBLEM 2BASIC CALCULATION
Solve: 63 ÷ 9 = ?
PROBLEM 3INTERMEDIATE
Use the break apart strategy to solve 7 × 8. Show your thinking! (Hint: break the 7 into two numbers that are easy to multiply by 8.)
PROBLEM 4WORD PROBLEM
A teacher has 54 colored pencils. She puts them into cups with 6 pencils in each cup. How many cups does she need? Then, 3 students each take 1 full cup. How many pencils are still on the teacher's desk?
PROBLEM 5CHALLENGE
Sam says, "I'm thinking of a number. When I multiply it by 8, I get the same answer as when I multiply 6 by 4." What is Sam's number? Explain how you figured it out using what you know about multiplication and division.

Lesson Review

In this lesson, you learned that multiplication means counting equal groups, and division means splitting into equal groups. The most important idea is that they are connected — if you know one fact, like 8 × 7 = 56, you can figure out the related division facts: 56 ÷ 8 = 7 and 56 ÷ 7 = 8. Three numbers that go together this way form a fact family with four facts.

You also learned powerful strategies to help you solve problems faster: using the fact family relationship, skip counting, the break apart strategy, doubling, and using 10s and subtracting for 9s facts. You can use arrays to see these facts as pictures. Keep practicing your facts every day, and soon you'll know them all by heart — and that will make every math topic that comes next much easier!

Varsity Tutors • 3rd Grade Mathematics (Common Core) • Multiply and Divide Within 100