K-5 friendly lesson
One small step at a time.Read the idea, try the activity, and celebrate each win as you go.
Relate multiplication and division for groups
Multiplication and division are best friends! 🤝 They are opposites, and they work together in families called "fact families". If you know one fact, you actually know four!
Do this: Read the concept below, then try the quiz or activity.
Lesson 75 of 220
Concept
Multiplication and division are inverse operations, which means they undo each other. For every multiplication fact, there are related division facts.
The Fact Family Triangle: Imagine you have 3 numbers that work together, like 5, 4, and 20. * We know that 4 groups of 5 make 20. (4 x 5 = 20) * We also know that 5 groups of 4 make 20. (5 x 4 = 20)
Now let's think about division. * If we start with 20 and we divide it into 4 equal groups, how many are in each group? 5! (20 ÷ 4 = 5) * If we start with 20 and we divide it into 5 equal groups, how many are in each group? 4! (20 ÷ 5 = 4)
The Whole Family: The fact family for 4, 5, and 20 is: * 4 x 5 = 20 * 5 x 4 = 20 * 20 ÷ 4 = 5 * 20 ÷ 5 = 4
Key Idea: When you see a division problem like 35 ÷ 7, you can ask yourself a multiplication question: "What number times 7 equals 35?". This 'thinking backwards' can make division much easier.
Try it
Practice: Relate multiplication and division for groups.