Basic Operations

The four elementary operations of arithmetic are addition, subtraction, multiplication and division.

Addition: It is a mathematical operation that represents the total amount of objects together in a collection. It is indicated by the plus sign (+). Addition rules are as follows.

Rule 1: (+a) + (+b) = (+ sign)

Rule 2: (+a) + (-b) = (– sign)

Rule 3: (-a) + (-b) = (– sign)

Examples

• (+10) + (+5) = (10 + 5) = (+15)
• (+4) + (-9) = (4 – 9) = (-5)
• (-4) + (-9) = (-13)

Subtraction: It is a mathematical operation that represents the operation of removing objects from a collection. It is signified by the minus sign (–). Subtraction riles are as follows.

Rule 1: (+a) – (+b) = (takes the sign of higher number)

Rule 2: (+a) – (-b) = (+ sign)

Rule 3: (-a) – (-b) = (if ‘a’ is greater than ‘b’, then it takes negative sign; if ‘b’ is greater than ‘a’, then it takes positive sign)

Examples

• 10 - 5 = 5
• (+4) – (+9) = (4 – 9) = (-5)
• (+4) – (-9) = (4 + 9) = (13)
• (-9) – (-4) = (-9) + 4 = (4 – 9) = (-5)
• (-4) – (-9) = (-4) + 9 = (9 – 4) = (5)

Multiplication: The multiplication of two whole numbers is equivalent to the addition of one of them with itself as many times as the value of the other one.

• (5 + 5 + 5 + 5 + 5 + 5 + 5) = 35 = (5 x 7)
• (4 + 4 + 4 + 4 + 4) = 20 = (4 x 5)

Rule 1: (+ sign) x (+ sign) = (+ sign)

Rule 2: (+ sign) x (– sign) = (– sign)

Rule 3: (– sign) x (– sign) = (+ sign)

Examples

• 6 x 6 = 36
• 52 x 12 = (52 x 10) + (52 x 2) = (520 + 104) = 624
• (+4) x (+8) = 32
• (+4) x (-8) = -32

Division: It is the process of determining the number of times one number (the DIVISOR) is contained in a second number (the DIVIDEND), the result being known as the QUOTIENT.

Rule 1: (+ sign) ÷ (+ sign) = (+ sign)

Rule 2: (+ sign) ÷ (– sign) = (– sign)

Rule 3: (– sign) ÷ (– sign) = (+ sign)

Examples

• (+8) ÷ (+4) = (+2)
• (+8) ÷ (-4) = (-2)
• (-8) ÷ (-4) = (+2)