LCM - Least Common Multiple

Quote: Mathematics is the door and key to the sciences.   ---Roger Bacon

Ex1. Find LCM 2 and 4?

Multiples of 2 : 2, 4, 6, 8,...
Multiples of 4 : 4, 8, 12, 16,...
Common multiples of 2 and 4 : 4, 8, ...
Least common multiple : 4

Rules from above example:

1. If one number is multiple of other number, the bigger number is LCM

2. To find LCM easily take the small number multiples and check multiple is divisible by bigger number. If yes, then the multiple is LCM

Ex2 : find LCM of 3 and 9?

LCM is 9 as 9 is divisible by 3.

Ex3. Find LCM of 4 and 6?

Small number is 4
Multiples of 4 : 4, 8, 12, 16, ...
Is 4 divisible by 6? No
Is 8 divisible by 6? No
Is 12 divisible by 6? Yes. So LCM is12

Ex4. Find LCM of 3 and 4?

multiples of 3: 3, 6, 9, 12, 15, 18, 21, ...
multiples of 4: 4, 8, 12, 16, 20, 24, 28, ...
So LCM is 12

Rule: if both the numbers doesn't have common factors, then LCM is product of two numbers.

Lets see how to find LCM  for more than two numbers in next post