Revision Notes Class 6 Mathematics Chapter 6 – Integers

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Revision Notes

Class 6 Mathematics

Chapter 6 Integers

Integers:

Ɣ The collection of all the whole numbers and their negatives are called the integers excluding the decimals or fractions. Ɣ The positive whole numbers are called the positive integers and the negative whole numbers are called the negative integers. Ɣ Even in our daily life we come across many examples where we use negative numbers such as for measuring temperature, for denoting the water level or elevation of a place with respect to main sea level, for showing outstanding amounts etc. Some examples of integers are; .... 4, 3, 2, 1,0,1,2,3,4.... .

Successors and predecessors:

A successor for both positive and negative integers can be found out by adding 1 to it. And similarly, the predecessor can be found out by subtraction 1 from the given integer.

Addition of integers:

Ɣ If the integers have the same sign, we simply add them and put the given sign in front. (i) When we add positive integers, we will get a positive integer. For example, ( 5) ( 8) 13 . (ii) When we add negative integers, we will get a negative integer. For example, ( 5) ( 8) 13 .

1. When integers with different signs are added, we subtract them like positive

whole numbers without considering their signs and then put the sign of a bigger one in the front which in turn is decided after removing the negative sign from the negative integer given. The two cases have been shown below. (i) Example - ( 7) ( 4) 3 (ii) Example - ( 7) ( 4) 3

Multiplication of integers:

The final sign after multiplication of integers is decided based on conventions tabulated below with examples;

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Sign of one

integer

Sign of another

integer

Final sign upon

multiplication

Example

() () () ( 4) ( 3) 12 () () () ( 4) ( 3) 12 () () () ( 4) ( 3) 12 () () () ( 4) ( 3) 12 Both addition and multiplication of integers can be shown on the number line by moving towards left from the point of reference for negative integers and towards right for positive integers.