12021

#include <stdio.h>
int main(){
double s;
int z, n, i;
scanf("%d", &z);
while (z-- != 0){
   scanf("%d", &n);
   s = 0;
   for (i=1; i<=n; i+=2){
    s += 1.0/i;
   }
   for (i=2; i<=n; i+=2){
    s -= 1.0/i;
   }
   printf("%.2lf
", s);
}
return 0;
}