# Program to find the LCM of two prime numbers

Given two prime numbers N and M, the task is to find the Least Common Multiple(LCM) of the two given prime numbers.

Examples:

Input: N = 3, M = 7
Output: 21
Explanation:
The least numbers greater than equals to 3 and 7 which is a multiple of 3 and 7 is 21.

Input: N = 5, M = 5
Output: 5
Explanation:
The least numbers greater than equals to 5 and 5 which is a multiple of 5 and 5 is 5.

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: As we know that product of two numbers equals to the product of their Greatest Common Divisor(GCD) and Least Common Multiple(LCM). So, the LCM of the two given prime numbers can be given by: .

Since the GCD two different prime numbers are 1, Therefore , and if the two given numbers are same then the LCM is the number itself.

Below is the implementation of the above approach:

## C++

 // C++ Program to find LCM of two  // prime numbers  #include  using namespace std;     // Function to return the LCM of two  // prime numbers  int findLCMPrime(int a, int b)  {      // If the two numbers are equal      // then return any one of a and b      if (a == b) {          return a;      }         // Else return product of numbers      return a * b;  }     // Driver code  int main()  {      // Given two numbers      int a = 3, b = 5;         // Function Call      cout << findLCMPrime(a, b);      return 0;  }

## Java

 // Java Program to find LCM of two  // prime numbers  class GFG{         // Function to return the LCM of two  // prime numbers  static int findLCMPrime(int a, int b)  {      // If the two numbers are equal      // then return any one of a and b      if (a == b)      {          return a;      }         // Else return product of numbers      return a * b;  }     // Driver code  public static void main (String[] args)  {      // Given two numbers      int a = 3, b = 5;         // Function Call      System.out.println(findLCMPrime(a, b));  }  }     // This code is contributed by AnkitRai01

## Python3

 # Python3 program to find LCM of two  # prime numbers     # Function to return the LCM of two  # prime numbers  def findLCMPrime(a, b):         # If the two numbers are equal      # then return any one of a and b      if (a == b):          return a;         # Else return product of the numbers      return a * b;     # Driver code  if __name__ == "__main__":         # Given two numbers      a = 3; b = 5;         # Function Call      print(findLCMPrime(a, b));     # This code is contributed by AnkitRai01

## C#

 // C# program to find LCM of two prime numbers   using System;     class GFG{          // Function to return the LCM of two   // prime numbers   static int findLCMPrime(int a, int b)   {              // If the two numbers are equal       // then return any one of a and b       if (a == b)       {           return a;       }              // Else return product of numbers       return a * b;   }          // Driver code   public static void Main (string[] args)   {              // Given two numbers       int a = 3, b = 5;              // Function Call       Console.WriteLine(findLCMPrime(a, b));   }   }      // This code is contributed by AnkitRai01

Output:

15


Time Complexity: O(1)

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Improved By : AnkitRai01