C program to find out the sum of given G.P

source code

#include<math.h>

int main()

{

    float a,r,i,tn;

    int n;

    float sum=0;

    printf("Enter the first number of the G.P. series: ");

    scanf("%f",&a);

    printf("Enter the total numbers in the G.P. series: ");

    scanf("%d",&n);

    printf("Enter the common ratio of G.P. series: ");

    scanf("%f",&r);

    sum = (a*(1 - pow(r,n+1)))/(1-r);

       tn = a * (1 -pow(r,n-1));

    printf("tn term of G.P.: %f",tn);

    printf("\nSum of the G.P.: %f",sum);

    getch();

    return 0;

}