The abbreviation LCM stands for 'Least Common Multiple'. The least common multiple (LCM) of two numbers is the lowest possible number that can be divisible by both numbers. It can be calculated for two or more numbers as well. There are different methods to find the LCM of a given set of numbers. One of the quickest ways to find the LCM of two numbers is to use the prime factorization of each number and then the product of the highest powers of the common prime factors will be the LCM of those numbers. Show
What is Least Common Multiple (LCM)?The least common multiple is also known as LCM (or) the lowest common multiple in math. The least common multiple of two or more numbers is the smallest number among all common multiples of the given numbers. Let us take two numbers, 2 and 5. Each will have its own set of multiples.
Now, let us represent these multiples on the number line and circle the common multiples. Thus, the common multiples of 2 and 5 are 10, 20, ….. The smallest number among 10, 20, … is 10. So the least common multiple of 2 and 5 is 10. It can be written as LCM (2, 5) = 10. How to Find LCM?LCM of numbers can be calculated using various methods. There are 3 methods to find the least common multiple of two numbers. Each method is explained below with some examples.
LCM by Listing MethodWe can find out the common multiples of two or more numbers by listing their multiples. Out of these common multiples, the least common multiple is considered and the LCM of two given numbers can thus be calculated. To calculate the LCM of the two numbers A and B by the listing method, we use the steps given below:
Example: Find the least common multiple (LCM) of 4 and 5. Solution: The first few multiples of 4 are: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, ... And the first few multiples of 5 are: 5, 10, 15, 20, 25, 30, 35, 40, ... We can observe that 20 is the least multiple which is common in the multiples of 4 and 5. Therefore, the least common multiple (LCM of 4 and 5) is 20. LCM by Prime Factorization MethodBy using the prime factorization method we can find out the LCM of the given numbers. To calculate the LCM of two numbers using the prime factorization method, we use the steps given below:
Let us learn this method using the example given below. Example: Find the least common multiple (LCM) of 60 and 90 using prime factorization. Solution: Let us find the LCM of 60 and 90 using the prime factorization method.
Therefore, LCM of 60 and 90 = 180. LCM by Division MethodIn order to find the LCM by division method, we divide the numbers by a common prime number, and these prime factors are used to calculate the LCM of those numbers. Let us understand this method using the steps given below:
Let us learn this method using the example given below. Example: Find the least common multiple (LCM) of 6 and 15 using the division method. Solution: Let us find the least common multiple (LCM) of 6 and 15 using the division method using the steps given below.
Though we have three methods to find the least common multiple, the division method is the most common and easy method that we use. Use the online LCM calculator to verify your answers. LCM FormulasLCM formulas are the collection of the numbers, their LCM, and their HCF (Highest Common Factor). These formulas are used to calculate the least common multiple of two integers as well as the LCM of two fractions. The LCM formulas for integers and fractions are shown below. LCM Formula for IntegersIf a and b are the two integers then the formula for their least common multiple is given as: LCM (a,b) = (a × b)/HCF(a,b) Relationship Between LCM and HCFThe Highest Common Factor (HCF) of a given set of numbers is the highest factor which is common among the factors of the given numbers. It is calculated by multiplying the common prime factors of the given numbers. Whereas the least common multiple (LCM) of two or more numbers is the smallest number among all common multiples of the given numbers. Let us assume a and b are the two numbers, then the formula that expresses the relationship between their LCM and HCF is given as: LCM (a,b) × HCF (a,b) = a × b or, Product of the two numbers = LCM of the numbers × HCF of the numbers Difference Between LCM and HCFThe HCF or the highest common factor of two or more numbers is the highest or the greatest factor among all the common factors of the given numbers, whereas the LCM or the least common multiple of two or more numbers is the smallest number among all common multiples of the given numbers. The following table shows the difference between HCF and LCM:
LCM of Three NumbersThe LCM of 3 numbers can be calculated using the same methods given above. Let us understand how to find the LCM of 25, 15, and 30 using the prime factorization method. Example: Find the LCM of 25, 15, and 30 using the prime factorization method. Solution: Let us use the following steps to find the LCM of the 3 numbers.
Now let us find the LCM of these 3 numbers by the listing method. Example: Find the LCM of 25, 15, and 30 by listing method. Solution: Let us use the following steps to find the LCM of the 3 numbers.
☛ Related Topics
go to slidego to slidego to slide
Have questions on basic mathematical concepts? Become a problem-solving champ using logic, not rules. Learn the why behind math with our certified experts Book a Free Trial Class
FAQs on Least Common Multiple (LCM)The least common multiple of two or more numbers is the lowest number that is a common multiple of the given numbers. If X and Y are two numbers such that X is a multiple of Y, then the LCM (X, Y) = X. The LCM of a given set of numbers cannot be less than any of the numbers except for 0 which can be considered as a common multiple of all whole numbers. How to Find the LCM?The least common multiple (LCM) of two or more numbers can be calculated using 3 methods:
What is the Fastest Way to Find the LCM?There are three methods to find the LCM of a given set of numbers - listing out the common multiples method, prime factorization method, and division method. The division method is the most common, the fastest, and the easiest of these three methods. It can be used for small or large numbers conveniently. A detailed explanation of finding the LCM by division method is given in the above sections in this page. What is the LCM of 12 and 9?The first few multiples of 12 are 12, 24, 36, 48, 60, 72, 84, ... and the first few multiples of 9 are 9, 18, 27, 36, 45, … The LCM of 12 and 9 will be the smallest multiple that is common to both the numbers. Thus, the LCM of 12 and 9 is 36. What is the Difference Between LCM and HCF?The least common multiple of two or more numbers is the smallest number among all common multiples of the given numbers and the HCF (Highest Common Factor) of two or more numbers is the highest number among all the common factors of the given numbers. What is the Relationship Between HCF and LCM of Two Numbers?Let us assume a and b are the two numbers. Then, the formula that expresses the relationship between their LCM and HCF is given as; LCM (a,b) × HCF (a,b) = a × b. This means, Product of two numbers = LCM of the numbers × HCF of the numbers What is the Least Common Multiple of 8 and 12?The LCM of 8 and 12 is the smallest number among all common multiples of both of the numbers. Multiples of 8 are 8, 16, 24, 32, 40, ... and the multiples of 12 are 12, 24, 36, ... Thus, the LCM of 12 and 8 is 24. How to Find LCM of 3 Numbers?The LCM of three numbers can be calculated using the same methods that are used to find the LCM of 2 numbers. Let us understand this with an example. Let us find the LCM of 3, 4, and 6 using the listing method.
How to Find LCM using Prime Factorization?In order to find the LCM of two numbers using prime factorization, we need to find the prime factors of the given numbers. For example, let us find the LCM of 6 and 8 using prime factorization.
What is the LCM of Two Coprime Numbers?The LCM of two coprime numbers is always their product. This is because they do not have any common factors other than 1. For example, let us take two coprime numbers, 4 and 9. Their LCM is 36. Let us check the LCM by using prime factorization, Prime factorization of 4 = 22 and 9 = 32. The product of these factors with the highest powers is 22 × 32 = 4 × 9 = 36. How is LCM used in Real Life?There are many situations in which the concept of LCM is used. For example, there are 3 boys who step off together and their steps measure 80 cm, 85 cm, and 90 cm respectively. If we need to find the minimum distance each should walk so that all can cover the same distance in complete steps, we will find their LCM. The LCM of 80, 85, and 90 is 12240 which is the required minimum distance that each should walk so that all can cover the same distance in . |