Average of the digits (string+funciton)

#include <stdio.h>
#include <string.h>

double Average(char n[])
{
    int len = strlen(n);
    int i, s = 0;

    for(i = 0; i < len; i++) {
        s += n[i] - '0';
    }
    return (double)s / (double)(strlen(n));
}

int main()
{
    char num[25];
    scanf("%s", num);

    double avg = Average(num);

    printf("%lf\n", avg);


    return 0;
}