Average, Geo and Harmonic mean calcl

Hello,

I am writing a program to read a series of numbers then calculate average, geometric mean and harmonic mean. I'm not sure if my formulas are entered correctly. Any thoughts, (not good at math)

Code:

/*this program will calculate the average, geometric mean and harmonic mean of a series of 5 pos numbers.

written by: Patricia Stephens

Date: June 2009

*/

#include<stdio.h>

#include "stdafx.h"

#include "math.h"

#define M 5

int main(void)

{

//local declarations

int i;

int sum;

int avg;

int n;

sum=avg=0;

//Statements

printf("please enter 5 whole numbers then key <EOF> to stop(CTRL+D OR CTRL + Z\n");

for (i=0; i<=M; i++)

{

scanf_s("%2d",&n);

sum=sum+n;

}

printf("the sum is %2d\n", ((sum)-n));

printf("the average is %2d\n", (int(sum)/n));

printf("the harmonic mean is %f\n", (n/float(sum)/1));

printf("the geometric mean is %f\n", pow(sum,1.0/n));

return 0;

}//main