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Prime Factors, HCF and LCM

Lowest Common Multiple (LCM)

The least common multiple of any two numbers a and b, denoted by LCM(a,b), is the smallest number that is divisible by both a and b.

To find the LCM of two numbers:

  • Express each number as a product of prime powers.
  • For each prime factor choose the prime power with largest exponent among all numbers.
  • The LCM is the product of the chosen prime powers.


Click on the question marks to see the example step by step.

LCM of 16 and 20 is 80

Find LCM(,).

LCM = 


Find the lowest common multiple (LCM) of the pairs of numbers.

Find LCM(,).

Working space

LCM = 

Another method for obtaining the LCM, is to find the HCF then

LCM equals product of numbers divided by thier HCF


LCM(18,24) equals 18 times 24 over HCF(18,24) equals 18 times 24 over 6 equals 72

<< Highest Common Factor | HCF andLCM Index |


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