C Program to Find LCM of two Numbers

Examples on different ways to calculate the LCM (Lowest Common Multiple) of two integers using loops and decision making statements.
To understand this example, you should have the knowledge of following C programming topics:
  • C Programming Operators
  • C if, if...else and Nested if...else Statement
  • C Programming while and do...while Loop
The LCM of two integers n1 and n2 is the smallest positive integer that is perfectly divisible by both n1 and n2 (without a remainder). For example: the LCM of 72 and 120 is 360. Read - Programming language

Example #1: LCM using while Loop and if Statement


#include <stdio.h>
int main()
{
    int n1, n2, minMultiple;
    printf("Enter two positive integers: ");
    scanf("%d %d", &n1, &n2);

    // maximum number between n1 and n2 is stored in minMultiple
    minMultiple = (n1>n2) ? n1 : n2;

    // Always true
    while(1)
    {
        if( minMultiple%n1==0 && minMultiple%n2==0 )
        {
            printf("The LCM of %d and %d is %d.", n1, n2,minMultiple);
            break;
        }
        ++minMultiple;
    }
    return 0;
}
Output
Enter two positive integers: 72
120
The LCM of 72 and 120 is 360.
In this program, the integers entered by the user are stored in variable n1 and n2respectively.
The largest number among n1 and n2 is stored in minMultiple. The LCM of two numbers cannot be less than minMultiple.
The test expression of while loop is always true (1). In each iteration, whether minMultiple is perfectly divisible by n1 and n2 is checked. If this test condition is not true, minMultiple is incremented by 1 and the iteration continues until the test expression of if statement is true.
The LCM of two numbers can also be found using the formula:
LCM = (num1*num2)/GCD
Learn more on, how to find the GCD of two numbers in C programming.

Example #2: LCM Calculation by Finding GCD

#include <stdio.h>
int main()
{
    int n1, n2, i, gcd, lcm;

    printf("Enter two positive integers: ");
    scanf("%d %d",&n1,&n2);

    for(i=1; i <= n1 && i <= n2; ++i)
    {
        // Checks if i is factor of both integers
        if(n1%i==0 && n2%i==0)
            gcd = i;
    }

    lcm = (n1*n2)/gcd;
    printf("The LCM of two numbers %d and %d is %d.", n1, n2, lcm);

    return 0;
}

Comments

Post a Comment

Popular posts from this blog

C Program to Check Whether a Character is an Alphabet or not

In this example, you will learn to check whether a character entered by the user is an alphabet or not. To understand this example, you should have the knowledge of following C programming topics: C Programming Operators C if, if...else and Nested if...else Statement Example: Program to Check Alphabet #include <stdio.h> int main () { char c ; printf ( "Enter a character: " ); scanf ( "%c" ,& c ); if ( ( c >= 'a' && c <= 'z' ) || ( c >= 'A' && c <= 'Z' )) printf ( "%c is an alphabet." , c ); else printf ( "%c is not an alphabet." , c ); return 0 ; } Output Enter a character: * * is not an alphabet In C programming, a character variable holds ASCII value (an integer number between 0 and 127) rather than that character itself. The ASCII value of lowercase alphabets are from
Read more

C Program to Calculate the Sum of Natural Numbers

To compute the sum of natural numbers from 1 to n (entered by the user), loops can be used. You will learn how to use for loop and while loop to solve this problem. To understand this example, you should have the knowledge of following C programming topics: C Programming for Loop C Programming while and do...while Loop The positive numbers 1, 2, 3... are known as natural numbers. The programs below takes a positive integer (let say  n ) as an input from the user and calculates the sum up to  n . Example #1: Sum of Natural Numbers Using for Loop #include <stdio.h> int main () { int n , i , sum = 0 ; printf ( "Enter a positive integer: " ); scanf ( "%d" ,& n ); for ( i = 1 ; i <= n ; ++ i ) { sum += i ; // sum = sum+i; } printf ( "Sum = %d" , sum ); return 0 ; } The above program takes the input from the user and stores in variabl
Read more

C Program to Check Whether a Number is Positive or Negative

In this example, you will learn to check whether a number (entered by the user) is negative or positive. To understand this example, you should have the knowledge of following C programming topics: C Programming Operators C if, if...else and Nested if...else Statement This program takes a number from the user and checks whether that number is either positive or negative or zero. Read -  Programming language Example #1: Check if a Number is Positive or Negative Using if...else #include <stdio.h> int main () { double number ; printf ( "Enter a number: " ); scanf ( "%lf" , & number ); if ( number <= 0.0 ) { if ( number == 0.0 ) printf ( "You entered 0." ); else printf ( "You entered a negative number." ); } else printf ( "You entered a positive number." ); return 0 ; } You can als
Read more