Integer addition and subtraction rules

Key Points:

🔹 What are Integers?

Integers are a set of whole numbers that include:

• Positive numbers (1, 2, 3, …)
• Negative numbers (–1, –2, –3, …)
• Zero (0)

👉 Example: –5, –2, 0, 3, 7 are all integers.

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🔹 Rules for Addition of Integers

Same Signs → Add and Keep the Sign

• If both integers are positive, add them and answer is positive.
• If both integers are negative, add them and answer is negative.
  ✅ Example:

• (+6) + (+3) = +9
• (–5) + (–4) = –9

Different Signs → Subtract and Keep the Sign of the Larger Number

• Subtract the smaller absolute value from the larger absolute value.
• The result takes the sign of the integer with the larger absolute value.
  ✅ Example:

• (+7) + (–3) = +4
• (–8) + (+5) = –3

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🔹 Rules for Subtraction of Integers

💡 Remember: Subtracting an integer is the same as adding its opposite.

Change subtraction into addition by taking the opposite of the second number.

a – b = a + (–b)

Then follow the rules of integer addition.

✅ Examples:

• 7 – (–4) = 7 + 4 = 11
• (–6) – (+3) = –6 + (–3) = –9
• (–8) – (–5) = –8 + 5 = –3

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🔹 Quick Tips

• “Like signs → Add”
• “Unlike signs → Subtract”
• “Subtracting a number → Add its opposite”

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🔹 Number Line Method (Visual Aid)

• Moving right → Positive direction
• Moving left → Negative direction
  👉 Example: (–2) + 5 = Start at –2, move 5 steps right → Answer = +3

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🔹 Practice Problems

1. (+9) + (–4) = ?
2. (–7) + (–6) = ?
3. (+12) – (–8) = ?
4. (–10) – (+5) = ?
5. (–3) + (+11) = ?

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✅ Answers:

1. +5
2. –13
3. +20
4. –15
5. +8

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📌 Summary:

Always check the sign of the bigger number for the final answer.

Addition of integers depends on signs (same → add, different → subtract).

Subtraction means adding the opposite.

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Learn with an example

Let’s practice!🖊️