**6.2 Addition and Subtraction of Integers**

6.2.1 Addition of Integers

1. Addition of integers can be done on a

**number line**.

**(a)** **To add a positive integer**:

Move to the

**right (positive direction)** on the number line.

(b) **To add a negative integer**:

Move to the

**left (negative direction)** on the number line.

2. Integers with the

**same signs** are called integers with

**like signs**.

*Example:*

2 and 7, –25 and –5.

**3. Integers** with the

**different signs** are called integers with

**unlike signs**.

*Example:*

+2 and –7, –25 and 5.

Example 1:

Solve the following.

(a) 3 + (+4)

(b) 2 + (–5)

*Solution:*

(a)

Therefore,

3 + (+4) = 3 + 4

= 7

**(b)**

Therefore,

2 + (–5)

= –3

**6.2.3 Multiplication and Division of Integers**

**1.** Multiplication and division of **like signs** gives (**+**)

$\overline{)\begin{array}{l}\text{}(+)\times (+)=+\text{}(+)\xf7(+)=+\text{}\\ \text{}(-)\times (-)=+\text{}(-)\xf7(-)=+\end{array}}$

2. Multiplication and division of **unlike signs** gives (**–**)

$\overline{)\begin{array}{l}\text{}(+)\times (-)=-\text{}(+)\xf7(-)=-\text{}\\ \text{}(-)\times (+)=-\text{}(-)\xf7(+)=-\end{array}}$

*Example:*

(a)

–25 ÷ 5 = –5

(b) 8 × (–5) = –40