How to Find HCF and LCM of numbers Easily, here is a Trick to Find HCF and LCM within Seconds in SSC, UPSC Competitive Examinations
Trick to Find HCF - Highest Common Factor
Lets find out HCF of 90 and 1261. Put Higher number as dividend and lower number as divisor
Dividend - The number which has to be divided
Divisor - The number with which the dividend has to be divided
In this case the higher number 126 is dividend and lower number 90 is divisor
90|126
90
------
36
2. Put the divisor as dividend and reminder as divisor in next step.
Here 90 is dividend and 36 is divisor
36| 90
72
-----
18
3. Repeat the step 2 until the reminder becomes zero
18| 36
36
----
0
4. Then HCF will be the last divisor. In this case HCF of 90 and 126 is 18
If More than two number's HCF is to be find out
First dividend is the highest number and first divisor is the second largest number. After finding first two numbers HCF the new dividend will be the next lowest number and the divisor will be the HCF of first two highest numbers.Trick to Find LCM - Least Common Factor
To Find LCM division method is used
Eg : Let's find out LCM of 9, 48 , and 21
1. Find out the Common factor
Here both 9, 48, 21 are divisible by 3 (How to Check Divisibility of a Number)
3 | 9, 48, 21
------------
3, 16, 7
2. Find Common factor for the divisors 3, 16, 7
No common factor for 3, 6, 7
So LCM = 3*3*16*7 = 1008
Another Eg : 72, 240, 196
2| 72, 240, 196
----------------
2|36, 120, 98
---------------
2|18, 60, 49
--------------3| 9, 30, 49 If the third number(49) is not divisible by 2 put it as 49
-------------
3, 10, 49
LCM = 2*2*2*3*3*10*49 = 35280
If you have any doubts regarding divisibility of a number please feel free to ask through the commenting system
COMMENTS