Area of circle C Program

Simple C program to calculate are of circle. How to find area of circle.

#include<stdio.h>
int main()
{
	float r,pi=3.14,area;
	printf("Enter radius of circle: ");
	scanf("%f",&r);
	area=pi*r*r;
	printf("Area of circle: ");
	/* .2 is for total digit after point*/
	printf("%.2f\n",area);
	return 0;
}