Monte Carlo Sphere

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
main()
{
    double x, y, z;
    double zupper, zlower, yupper, ylower, xupper, xlower;
    double montevol,volume;
    double totalexpvol, totalvol;

int j;
int iterations;

printf("enter lower x limit\n");
  scanf("%lf", &xlower);
printf("enter upper x limit\n");
  scanf("%lf", &xupper);
printf("xlower %lf xupper %lf\n", xlower, xupper);
printf("enter lower y limit\n");
  scanf("%lf", &ylower);
printf("enter upper y limit\n");
  scanf("%lf", &yupper);
printf("ylower %lf yupper %lf\n", ylower, yupper);
printf("enter lower z limit\n");
  scanf("%lf", &zlower);
printf("enter upper z limit\n");
  scanf("%lf", &zupper);
printf("zlower %lf zupper %lf\n", zlower, zupper);

    volume = (xupper - xlower)*(yupper - ylower)*(zupper - zlower);
printf("volume is %lf\n", volume);
printf("enter iterations up to 1000000\n");
  scanf("%d", &iterations);

totalvol = 0;
totalexpvol = 0;

for (j = 1;j < iterations;j++)
{
    /* find random numbers for x,y and z */

x = rand() % 1000;
y = rand() % 1000;
z = rand() % 1000;

y = y / 1000;
x = x / 1000;
z = z / 1000;

      /* x,y and z will have numbers between 0 and 1 */
      /* so multiply by the user's entered ranges for x,y and z */

x = xlower + (xupper - xlower)*x;
y = ylower + (yupper - ylower)*y;
z = zlower + (zupper - zlower)*z;

if (x >= xlower && z >= zlower && y >= ylower)
{
    totalvol = totalvol + 1; /* This contains the total number of entries */

if ((pow(y, 2) + pow(x, 2) + pow(z, 2)) < 4)
{
  totalexpvol = totalexpvol + 1;/* This contains number of entries within desired vol */
}
}
}

if (totalvol != 0)

{
montevol = volume * (totalexpvol / totalvol);/* Monte Carlo volume os the fraction of the cube volume */
}
printf("monte carlo volume is %lf\n", montevol);
}