Program to Find LCM and HCF of two numbers

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Program to Find LCM and HCF of two numbers
vinaykhatri

Vinay Khatri
Last updated on February 28, 2024

    LCM stands for Least Common Multiple, and HCF stands for Highest common factor. Finding LCM and HCF of two numbers is an elementary school math problem. The HCF is also known as GCD (Greatest Common Divisor). You may know how to calculate LCM and HCF of two numbers using pen and paper.

    Now, let's write a program that can accept two numbers from the user and return their LCM and HCF.

    C Program to Find LCM and HCF of two numbers

    #include <stdio.h>
    
    int main() 
    {
        int num1, num2, min, max, r, lcm , hcf;
        
        //ask user to enter both the numbers 
        printf("Enter two numbers (eg 12 5): ");
        scanf("%d %d", &num1, &num2);
        
        //compare both the number
        //find out maximum and minimum number
        if(num1>num2)
        {
        	max= num1;
        	min= num2;
    	}
    	else if(num2> num1)
    	{
    		max= num2;
    		min = num1;
    	}
    	
    	//if both the numbers are same
    	//both the numbers are the HCF itself
    	if(num1==num2)
    	{
    		hcf=num1;
    	}
    	//if numbers are not same
    	else
    	{
    		do
    		{
    			//find the remainder
    			r = max%min;
    			//now set the divisor to maximum
    			//and remainder to minimum
    			max= min;
    			min=r;
    		}while(r!=0);  //keep looping until remainder become 0
    		hcf = max;
    	}
    	
    	lcm = (num1*num2)/hcf;
    	printf("The HCF of %d %d is %d\n", num1, num2, hcf);
    	
    	printf("The LCM of %d %d is %d", num1, num2, lcm);
    	return 0;
    }

    Output

    Enter two numbers (eg 12 5): 10 3
    The HCF of 10 3 is 1
    The LCM of 10 3 is 30

    C++ Program to Find LCM and HCF of two numbers

    #include <iostream>
    using namespace std;
    
    int main() 
    {
         int num1, num2, min, max, r, lcm , hcf;
        
        //ask user to enter both the numbers 
        cout<<"Enter two numbers (eg 12 5): "; cin>>num1>> num2;
        
        //compare both the number
        //find out maximum and minimum number
        if(num1>num2)
        {
        	max= num1;
        	min= num2;
    	}
    	else if(num2> num1)
    	{
    		max= num2;
    		min = num1;
    	}
    	
    	//if both the numbers are same
    	//both the numbers are the HCF itself
    	if(num1==num2)
    	{
    		hcf=num1;
    	}
    	//if numbers are not same
    	else
    	{
    		do
    		{
    			//find the remainder
    			r = max%min;
    			//now set the divisor to maximum
    			//and remainder to minimum
    			max= min;
    			min=r;
    		}while(r!=0);  //keep looping until remainder become 0
    		hcf = max;
    	}
    	
    	lcm = (num1*num2)/hcf;
    	cout<<"The HCF of "<< num1<<" "<< num2<<" is "<< hcf<<endl;
    	
    	cout<<"The LCM of "<<num1 <<" "<<num2<<" is " <<lcm;
            return 0;
    }

    Output

    Enter two numbers (eg 12 5): 500 7
    The HCF of 500 7 is 1
    The LCM of 500 7 is 3500

    Python Program to Find LCM and HCF of two numbers

    num1, num2 = map(int, input("Enter two numbers (eg 12 5): ").split())
    # if both the numbers are same
    # both the numbers are the HCF itself
    if num1==num2:
        hcf = num1
        lcm = num1
    
    # if numbers are not same
    else:
        # find out maximum and minimum number
        maxi = max(num1, num2)
        mini = min(num1, num2)
    
        if maxi%mini ==0:
            hcf = mini
        else:
            while(maxi%mini):
                # find the remainder
                # set the divisor to maximum
                # and remainder to minimum
                r= maxi%mini
                maxi = mini
                mini = r
            hcf = mini
            lcm = (num1*num2)//hcf
    
    print(f"The HCF of {num1} {num2} is:",hcf )
    print(f"The LCM of {num1} {num2} is:", lcm)

    Output

    Enter two numbers (eg 12 5): 320 128
    The HCF of 320 128 is: 64
    The LCM of 320 128 is: 640

    Conclusion

    In this programming article, you learned how to find the HCF and LCM of two numbers in 3 different programming languages. Finding LCM and HCF is also one of the most common interview questions. Carefully read and implement the above program of your own so that you won't get confused in the interview.

    If you like the above article and have any suggestions or queries, feel free to let us know by commenting down below.

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