C Program to Find Lowest Common Multiplication (LCM)

Before coding the C program to find LCM of a two number you must know about

if statement in C

if else statement

C while loop

LCM is the lowest positive number that is perfectly divisible by both given numbers. For example, LCM of 20 and 30 is 60.

C program to calculate LCM of two number using if-else statement and while loop.

#include<stdio.h> #include<conio.h> void main() {      int a, b, max;      printf("\n Enter First positive number");      scanf("%d", &a);      printf("\n Enter Second positive number");      scanf("%d", &b);      if(a>b)      {           max=a;      }      else      {           max=b;      }      while(1) //always true      {           if(max%a==0&&max%b==0)           {               printf("\n LCM of %d and %d is %d", a, b, max);               break;           }           max++;      }           getch(); }

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Output

• In this program, the first integer given by the user is stored in the variable a.
• Similarly, the second positive number is stored in variable b.
• Moreover, the if-else statement checks the largest number between a and b the maximum number hold by the variable max.
• In each iteration the condition if(max%a==0&&max%b==0) is checked.
• If the condition does not satisfy then out of the part of if statement max++; increase the value of max by 1. And the process will be repeated until the condition satisfied.

Example:

Let the user entered First positive number is 5. It is stored in a variable. And the second number is 4. (it is stored in b variable)  The part if(a>b)      {           max=a;      }      else      {           max=b;      } Check the largest number 4 and 5 and the largest number is 5 while(1) is always true   if(max%a==0&&max%b==0) check the condition as (5%4==0&&5%5==0) it is false because 5 is not divisible by 4.   max++; Increase the value of max by 1 and 5 convert into 5+1 then the max becomes 6   Continuously, The process will be continue until the condition if(max%a==0&&max%b==0) is true.   When value of max reach 20 printf("\n LCM of %d and %d is %d", a, b, max); print the LCM of 4 and 5 is 20   break; End the program.

C program to calculate LCM of two number greatest common divisible (GDC)

LCM = ( number 1 * number 3)/GCD

#include<stdio.h> #include<conio.h> void main() {      int a, b, i, gdc, lcm;      printf("\n Enter First positive number");      scanf("%d", &a);      printf("\n Enter Second positive number");      scanf("%d", &b);      for(i=1;i<a&&i<b;++i)      {           if(a%i==0&&b%i==0)           {           gdc = i;            }      }      lcm = (a*b)/gdc;      printf("\n LCM of %d and %d is %d", a, b, lcm); }

Output

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• In this program, the first integer given by the user is stored in the variable a.
• Similarly, the second positive number is stored in variable b.
• for(i=1;i<a&&i<b;++i) iteration executes if both a and b are exactly divisible by i.
• if(a%i==0&&b%i==0) Condition checks the a and b is exactly divisible by i. If the condition is true then the GDC is i.
• (a*b)/gdc; Find the LCM of a and b.