Addition of Integers

1. Addition of Integers

2. Objectives
At the end of this lesson, the learner should be able to
 correctly add integers; and
 accurately solve word problems involving addition of
integers.

3. Essential Questions
 How is adding integers different from adding whole
numbers?
 How does the sign of the integers affect its sum?

4. Learn about It!
Rules in Adding Integers
If two or more integers have the same sign, add the numbers and copy the
common sign.
The sum of two or more positive integers is also a positive integer.
1
Example:
4 + 8 = 12
Both addends are positive that is why the sum is also positive.

5. Learn about It!
Rules in Adding Integers
If two or more integers have the same sign, add the numbers and copy the
common sign.
The sum of two or more negative integers is also a negative integer.
1
Example:
−5 + (−13) = −18
Both addends are negative that is why the sum is also negative.

6. Learn about It!
Rules in Adding Integers
If two integers have different sign, subtract the numbers (disregarding the sign)
and copy the sign of the integer farther from zero.
1
Example:
9 + −4 = 5
The addends have different sign, so we subtract 9 and 4 then
copy the sign of 9 since it is farther from zero as compared to
− 4.

7. Learn about It!
Rules in Adding Integers
If two integers have different sign, subtract the numbers (disregarding the sign)
and copy the sign of the integer farther from zero.
1
Example:
−13 + 6 = −7
The addends have different sign, so we subtract 13 and 6
then copy the sign of −13 since it is farther from zero as
compared to 6.

8. Try It!
Example 1: What is the sum of −67 and −105?

9. Try It!
Solution:
1. Identify the sign of the addends.
The addends have the same sign which is negative.
2. Identify what rule to apply.
If two integers have the same sign, add the numbers and
copy the common sign.
Example 1: What is the sum of −67 and −105?

10. Try It!
Solution:
3. Add the integers based on the rule.
−67 + −105 = −172
Recall that the sum of two or more negative integers is also
a negative integer.
Thus, the sum of −67 and −105 is −𝟏𝟕𝟐.
Example 1: What is the sum of −67 and −105?

11. Try It!
Example 2: Find the value of 94 + (−43).

12. Try It!
Solution:
1. Identify the sign of the addends.
The addends have the different signs.
2. Identify what rule to apply.
If two integers have different sign, subtract the numbers
(disregarding the sign) and copy the sign of the integer
farther from zero.
Example 2: Find the value of 94 + (−43).

13. Try It!
Solution:
3. Add the integers based on the rule.
94 + −43 = 51
We subtract 94 and 43 and copy the sign of the integer
farther from 0 which is 94.
Thus, the value of 94 + (−43) is 𝟓𝟏.
Example 2: Find the value of 94 + (−43).

14. Let’s Practice!
Individual Practice:
1. What is the sum of −68, −29, and −132?
2. What is the value of 34 + −56 + (−18)?

15. Let’s Practice!
Practice:
A submarine is 53 feet below the sea level. If it moves 15 feet
above, at what depth is it now?

16. Key Points
Rules in Adding Integers
1. If two or more integers have the same sign, add the numbers and copy the
common sign.
2. If two integers have different sign, subtract the numbers (disregarding the
sign) and copy the sign of the integer farther from zero.
1

17. Synthesis
 How do we add integers?

18. Task
Do page 141, Individual Work (A and B)