# 1.2.1 Basic Arithmetic Operations Involving Integers

1.2.1 Basic Arithmetic Operations Involving Integers

1.2.1a Multiplication and Division of Integers

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

$\overline{)\begin{array}{l}\text{}\left(+\right)×\left(+\right)=+\text{}\left(+\right)÷\left(+\right)=+\text{}\\ \text{}\left(-\right)×\left(-\right)=+\text{}\left(-\right)÷\left(-\right)=+\end{array}}$

2.
Multiplication and division of unlike signs gives ()

$\overline{)\begin{array}{l}\text{}\left(+\right)×\left(-\right)=-\text{}\left(+\right)÷\left(-\right)=-\text{}\\ \text{}\left(-\right)×\left(+\right)=-\text{}\left(-\right)÷\left(+\right)=-\end{array}}$

Example:
(a) –25 ÷ 5 = –5
(b)   8 × (–5) = –40

3.
Multiplication of 3 integers.

$\overline{)\begin{array}{l}\text{}\left(+\right)×\left(+\right)×\left(+\right)=\left(+\right)\text{}\\ \text{}\left(+\right)×\left(+\right)×\left(-\right)=\left(-\right)\\ \text{}\left(+\right)×\left(-\right)×\left(-\right)=\left(+\right)\text{}\end{array}}$

4.
Division of 3 integers.

$\overline{)\begin{array}{l}\text{}\left(+\right)÷\left(+\right)÷\left(+\right)=\left(+\right)\text{}\\ \text{}\left(+\right)÷\left(+\right)÷\left(-\right)=\left(-\right)\\ \text{}\left(+\right)÷\left(-\right)÷\left(-\right)=\left(+\right)\text{}\end{array}}$

5.
The product of an integer and zero is always zero.
Example:
–5 × 0 = 0

6.
When zero is divided by any integer except zero, the quotient is zero. Any integer divided by zero is undefined.
Example:
(a) 0 ÷ 9 = 0
(b)   –6 ÷ 0 is undefined

1.2.1b Combined Operations of Integers

1. BODMAS(Brackets of Division, Multiplication, Addition and Subtraction)

 1. Operations in the brackets should be carried out first.  2. Followed by × or ÷ from left to right.  3. Followed by + or – from left to right.

Example 1:
(a) –52 ÷ 13 – 15 × 4
(b)   63 ÷ (16 – 7) × (–2)
(c) –30 + 9 × 7 – 16

Solution:
(a)
–52 ÷ 13 – 15 × 4
= (–52 ÷ 13) – (15 × 4) ← (calculate from left to right; ÷ and × are done first)
= –4 – 60
= –64

(b)
63 ÷ (16 – 7) × (–2)
= 63 ÷ 9 × (–2) ← (bracket is done first, then work from left to right)
= 7 × (–2)
= –14

(c)
–30 + 9 × 7 – 16
= –30 + (9 × 7) – 16 ← ( multiply first)
= –30 + 63 – 16
= 17

### 2 thoughts on “1.2.1 Basic Arithmetic Operations Involving Integers”

1. its really help me to do my maths revision
Tq so much :*

• You are welcome 🙂