The Four Rules of Operations

Maths: Edexcel IGCSE Higher, topic 1.1.3

The Four Rules for Positive Numbers

You should be able to calculate the sum, difference, product and quotient of numbers without using a calculator.

Calculating the difference means subtracting one number from another.
E.g. 4 - 2 = 2
You may have noticed that the sum and difference are reverse functions of each other.

Calculating the product means multiplying two numbers together.
E.g. 3 x 3 = 9
To understand multiplication you need to have a good understanding of times tables.

Calculating the quotient means dividing one number by another number.
E.g. 9 ÷ 3 = 3
You may have noticed that the product and quotient are reverse functions of each other.

You should be able to calculate: the sum, difference, product and quotient of negative numbers as well as positive numbers.

When calculating the sum of two negative numbers, you go down the number scale away from 0.

When you multiply two negative numbers together, the product is positive.
But when you multiply one negative number by one positive number the product is always negative.

When both numbers in the division calculation are negative, the quotient is positive.
When one number in the division calculation is negative and the other is positive, the quotient is negative.

Calculating the sum and difference:
If the calculation's function (the + or −) is the same as the sign in front of the 2nd number in the equation, the answer will be positive.
If the calculation's function (the + or −) is different to the sign in front of the 2nd number in the equation, the answer will be negative.
Calculating the product and quotient:
If the numbers in the equation are either both positive or both negative, the answer will be a positive number.
If one number in the equation is positive and the other is negative, the answer will be a negative number.