Connection: Addition and Subtraction are Related
Understand how addition and subtraction are inverse operations.
🎯 What You'll Learn
You will discover that addition and subtraction are opposite operations — knowing one helps you solve the other!
🏪 Market Story
Bola buys 3 oranges and then buys 5 more. She has 8 oranges (3 + 5 = 8). Later, she gives 5 oranges away. She's back to 3 (8 − 5 = 3). Addition and subtraction undo each other!
📝 Let's Learn
Addition and subtraction are inverse operations — they are opposites that undo each other.
If you know: 7 + 5 = 12, then you also know:
- 12 − 5 = 7
- 12 − 7 = 5
These three facts are called a fact family. Here's another: 8 + 4 = 12, so 12 − 4 = 8 and 12 − 8 = 4.
Example 1: 6 + 9 = 15, so 15 − 9 = 6 and 15 − 6 = 9.
Example 2: If ₦50 + ₦30 = ₦80, then ₦80 − ₦30 = ₦50.
Example 3: You know 25 + 75 = 100. So 100 − 75 = 25 and 100 − 25 = 75.
How to use this: If you need to solve 13 − 8 = ?, think: 8 + ? = 13. The answer is 5, because 8 + 5 = 13.
✏️ Practice Questions
- If 9 + 7 = 16, what is 16 − 7?
- If ₦120 + ₦80 = ₦200, what is ₦200 − ₦120?
- Solve 15 − 9 by thinking: 9 + ? = 15.
Click to see answers
- 16 − 7 = 9.
- ₦200 − ₦120 = ₦80.
- 9 + 6 = 15, so 15 − 9 = 6.
💡 Remember
Addition and subtraction are a team! If you know one fact, you know three. Use addition to check your subtraction and subtraction to check your addition.