Least Common Multiple (L.C.M)

Factorisation of Class 7

How to find LCM

The least number which is exactly divisible by one of the given numbers is called their L.C.M.

Methods of finding the L.C.M of a given set of numbers.

  • Factorization Method: Each one of the given numbers is first resolved into a product of prime factors. Then, L.C.M. is the product of highest powers of all the factors.
  • Common Division Method (Short-cut Method) of Finding L.C.M.: Arrange the given numbers in a row in any order. Divide by a number which divides exactly at least two of the given numbers and carry forward the numbers which are not divisible. Repeat the above process till no two of the numbers are divisible by the same number except 1. The product of the divisors and the undivided numbers is the required L.C.M. of the given numbers.

Product of two Numbers:

H.C.F. of numbers × L.C.M. of numbers = Product of numbers

i.e., if the numbers are A and B then

(H.C.F. of A and B) × (L.C.M. of A and B) = A × B

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