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**Factor :**A number is said to be a factor of other when itthe other.__EXACTLY divides__- Ex : 6 and 7 are Factors of 42.
**Multiple :**A number is said to be a multiple of another, when it is__Exactly divisible__by the other- Ex : 42 is a multiple of 6 and 7

Please re - read these definitions. So that you can get the difference between Factor and Multiple.

**Prime Number :**Prime number is a number which has no factors except itself and Unity.- Ex :2, 3, 5, 7, 11, 13, 17 etc are prime numbers
**Composite Number :**Composite number is a number which has other factors besides itself and Unity.- Ex : 14, 15, 16, 18 etc
**Co-Prime :**Two numbers are said to be Co-Prime (Prime-To-Each Other) when they have no common factors except Unity.- Note : The Co-Primes need not necessarily be Primes.
- 15 and 19
- 15, 17 and 22 are Co-Primes
**Common Multiple :**A Common Multiple of two or more numbers is a number which is exactly divisible by each of them.**Ex :**12 is a common multiple of 2, 3, 4 and 6**Least Common Multiple (LCM) :**The LCM of two or more given numbers is the Least Number which is exactly divisible by each of them.**Ex :**- 20 is the Common Multiple of 2, 4, 5 and 10
- 40 is the Common Multiple of 2, 4, 5 and 10
- 80 is the Common Multiple of 2, 4, 5 and 10, But
- Here 20 is the Least Common Multiple of 2, 4, 5, and 10
**Highest Common Factor (HCF) :**The HCF of two or more numbers is the Greatest Number which divides each of them Exactly.- It is also Called
**Greatest Common Divisor (GCD)** **Ex :**Find the HCF of 18, 24- Factors of 18 --> 1, 2, 3, 6, 9, 18
- Factors of 24 --> 1, 2, 3, 4, 6, 8, 12, 24
- Here the Greatest number, which divides them exactly is 6. So 6 is the H.C.F of 18, 24

In the above example they have given very small numbers. So it was easy for us to find the HCF. What if they ask you to find the HCF for 84 and 540 ? Will you write the factors to both of them and then find out the Highest number? If you are planning to do that , please erase that thought from your mind :) Because there are several methods to make the process simple

**Methods of finding HCF :**

**HCF by factorization :**- Express each of the given number as the product of Prime Factors
- Choose common factors
- Find the Product of Lowest Power of these Factors.
- This Product is the required HCF of the given Numbers

**Ex : Find the HCF of 84, 540**

**HCF by Method of Division :**- Consider two different numbers.
- Divide the longer number by the smaller one.
- Now divide the divisor by the reminder.
- Repeat this process of dividing the preceding divisor by the last reminder obtained, till you get the reminder "0"
- The LAST DIVISOR is the HCF of the given TWO numbers

**Ex : Find the HCF of 42, 70**

i hav doubt in lcm ,u said 40 cmn mul r 2, 4, 5, 10 y v shouldn't include 8 also , pls explain . .

ReplyDeleteWell it seems you dint get the concept...

DeleteSee, here we are talking about the COMMON MULTIPLES of the given numbers.

Assume that you've taken 8 too into consideration...

80 is the common multiple of 2, 4, 5, 8 and 10

40 is the common multiple of 2, 4, 5, 8 and 10

but what about 20? Its not the multiple of 8 no? That's the reason why we dint took 8 into consideration for this example :)

Hope we've cleared your doubt. Happy Reading

ya sir i got it now , thanks for ur kind reply

ReplyDeleteHello sir in the above answer u said didn't took so is day a right one while writing r speaking I'm. Getting confusion pls explain me sir

ReplyDeleteI'm a Maths teacher Naresh... Usually maths teachers don't have good English speaking skills... That't the reason why dint took :D

ReplyDelete(well, sorry for the mistake.. I was in a hurry while responding to that message and you should use TAKE)

Thank you so much for the correction. Good day.....

u had given wrong examples for composite number's ma'am. they are 4,6,8,9,...but not 14,16,18....this minor mistakes makes me to get cmpletely confused for a while.

ReplyDeleteYou are still in confusion Srinu Rao.. see

Delete14 is a composite number because it has other factors besides itself and unity (2x7, 7x2)

16 is a composite number because it has other factors besides itself and unity (2x8, 4x4, 2x8)

18 is a composite number because it has other factors besides itself and unity (2x9, 3x6, 6x3, 9x2)

hope you got it now :)

Very impressive

ReplyDeletemind blowing yar.. :)

ReplyDeleteHi how to find LCM of 1.20,30,40 2.10,15

ReplyDeletekindly explain HCF

ReplyDeletekindly how to find LCM for 52,46,58 clear explain

ReplyDeleteShiv RK-u r a nice person...

ReplyDeleteI just want to know some short cut tricks on maths

ReplyDeleteI am a grt fan of u-Shiv RK...

ReplyDelete