Write a program to find GCD and LCM of two positive integer values.

The Greatest Common Divisor(GCD) of two or more numbers is the largest non-zero positive number by which all the given numbers are divisible. For example, the GCD of 8 and 12 is 4.

The Least Common Multiple (LCM) or Smallest Common Multiple of two or more numbers is the smallest non-zero positive integer that is divisible by all the given numbers. For example, LCM of 4 and 6 is 12.

The relation between GCD and LCM is

Product of numbers = GCD * LCM

#include <stdio.h>
int main()
{
 	int a,a1,b,b1,c,gcd,lcm;
 	printf("Enter First Number : ");
 	scanf("%d",&a);
	printf("Enter Second Number : ");
	scanf("%d",&b);
 	a1=a;
 	b1=b;
 	if(a > b)
 	{
 		c=a;
 		a=b;
 		b=c;
 	}
 	while(b%a!=0)
 	{
 		c=b%a;
 		b=a;
 		a=c;
 	}
 	gcd=a;
 	lcm=(a1*b1)/gcd;
 	printf("GCD is %d\n",gcd);
 	printf("LCM is %d\n",lcm);
}

Output

========

Enter First Number : 25

Enter Second Number : 15

GCD is 5

LCM is 75