Day 2: Adding & Subtracting Integers 🧮
Middle Stage (Grades 6, 7 & 8) | Apex Institute of Maths and Sciences
🎯 1. Concept: Math with Positives and Negatives
Welcome back! Yesterday we learned that Integers live on the number line. Today, we are going to learn how to add and subtract them. It can look confusing when you see lots of plus and minus signs together, but it becomes very easy if you think about Money and Debt.
- Positive Numbers (+) = Money you HAVE in your pocket.
- Negative Numbers (-) = Debt (money you OWE to someone else).
💡 2. The Golden Rules of Integers
Rule 1: Adding a Negative (Debt)
Think: You have ₹5, but you add a debt of ₹3.
Math: 5 + (-3) = 2. (It’s just like regular subtraction: 5 – 3 = 2).
Rule 2: Combining Debts
Think: You owe ₹4, and then you borrow ₹2 more. Your debt grows!
Math: -4 – 2 = -6.
Rule 3: Subtracting a Negative (The Double Minus!)
Think: Someone takes away a ₹3 debt you owed them. That’s a good thing! It’s like gaining money.
Math: 5 – (-3) = 8. (When you see two minus signs together, they combine into a PLUS: 5 + 3 = 8).
🌍 3. Math in Our Daily Life
Let’s look at how temperature changes using integers!
Scenario 1 (Dropping Temps): The temperature in Manali is 4°C. During the night, it drops by 7 degrees. What is the temperature now?
Calculation: 4 – 7 = -3°C.
Scenario 2 (Warming Up): The temperature in a freezer is -5°C. The power goes out, and it warms up by 5 degrees.
Calculation: -5 + 5 = 0°C (Exactly freezing point!).
📝 4. Application Tasks
Grab your math journal and try these real-world scenarios:
- Task A: The Bank Account: You have a bank balance of -₹200 (you owe the bank). You deposit ₹500. Write the integer equation and find your new balance.
- Task B: The Double Negative: Write down your own example of “Subtracting a Negative” (e.g., 10 – (-5)). Explain in your own words why it turns into addition.
- Task C: The Elevator: Start at floor -2 (basement level 2). Go up 5 floors. What floor are you on now? Write the equation.
✅ 5. Day 2 Practice Test
Let’s put your new skills to the test! Select the correct answers below and click submit to check your score.
