POINTS RELATED TO CHAPTER –
FACTORS AND MULTIPLES
CLASS 5th, 6th, 7th & 8th
POINTS TO REMEMBER:-
1) A factor of a number is an exact divisor of that number and the number has a finite number
of factors.
2) A multiple of a number is exactly divisible by that number and the number can have an
infinite number of multiples.
3) Suppose a number x divides a number y exactly. Then, we say that x is a factor of y. Also in
this case, we say that y is a multiple of x.
4) Every number is a factor and a multiple of itself.
5) 1 is a factor of every number.
6) 1 is the only number having exactly one factor.
7) A number having exactly two factors is called a prime number.
8) A number having more than two factors is called a composite number.
9) 2 is the smallest and only even prime number.
10) Number 1 is neither prime nor composite.
11) A number is divisible –
i) by 2, if its one digit is any of 0, 2, 4, 6, 8.
ii) by 3, if the sum of its digits is divisible by 3.
iii) by 9, if the sum of its digits is divisible by 9.
iv) by 5, if its ones digit is 0 or 5.
v) by6, if it is divisible by both 2 and 3.
vi) by 4, the number formed by the tens and ones digits is divisible by 4.
vii) by 8, if the number formed by hundreds, tens and ones digits is divisible by 8.
viii) by 11, if the difference of the sum of the digits at odd places and the sum of the digits at
even places is either 0 or multiple of 11.
12) The product of the HCF and LCM of two numbers is equal to the product of the numbers. i.e.
HCF *LCM = product of the two numbers.
13) HCF of two numbers is a factor of their LCM.