Definition of LCM (Least common multiple):

LCM of two integers is a smallest positive integer which is multiple of both integers that it is divisible by the both of the numbers.
For example: LCM of two integers 2 and 5 is 10 since 10 is the smallest positive numbers which is divisible by both 2 and 5.
LCM program in c with two numbers :

‪#‎include‬<stdio.h>
int main(){
int n1,n2,x,y;
printf("\nEnter two numbers:");
scanf("%d %d",&n1,&n2);
x=n1,y=n2;
while(n1!=n2){
if(n1>n2)
n1=n1-n2;
else
n2=n2-n1;
}
printf("L.C.M=%d",x*y/n1);
return 0;
}