# Knowing Our Numbers Class 6 Maths Notes

Knowing our Numbers

• Large numbers upto one crore
• Reading and writing of large numbers
• Comparing large numbers
• Indian System of Numeration
• International System of Numeration
• Use of large numbers
• Estimation of numbers

• Use of brackets
• Roman numerals

Whole Numbers

• Natural numbers
• Predecessor and successor of a natural number
• Whole numbers: The natural numbers along with zero form the collection of whole numbers.
• Representation of whole numbers on the number line
• Addition and subtraction of whole numbers on the number line
• Division of a whole number by zero is not defined

• Patterns in whole numbers

Properties of whole numbers

• Closure property
• Commutativity of addition and multiplication
• Distributivity of muliplication over addition
• Identities for addition and multiplication

Playing with Numbers

• Factors and multiples
• Number of factors of a given number is finite
• Number of multiples of a given number is infinite

• Perfect number: A number for which sum of all its factors is equal to twice the number.
• Prime and composite numbers
• Tests for divisiblity of numbers by 2, 3, 4, 5, 6, 8, 9 and 11
• Common factors and common multiples
• Coprime numbers

Divisibility rules

• Product of two consecutive whole numbers is divisible by 2
• If a number is divisible by another number, then it is divisible by each of the factors of that number.
• If a number is divisible by two coprime numbers, then it is divisibile by their product also.
• If two given numbers are divisible by a number, then their sum is also divisible by that number.
• If two given numbers are divisible by a number, then their difference is also divisible by that number.

Prime factorisation of a number

• Highest Common Factor (HCF) of two or more numbers
• Least Common Multiple (LCM) of two or more numbers
• Use of HCF and LCM in problems of day to day life.