Codeforces Gym 100796F - Unusual Sum Problem_Solution

/*
Tanzila Islam
Southeast University
mail : tanzilamohita@gmail.com
Problem Link : http://codeforces.com/gym/100796/problem/F
*/
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cmath>
using namespace std;

int main(){

    int t;

    double l, r;

    scanf("%d", &t);

    while(t--){

        scanf("%lf%lf", &l, &r);

        printf("%.12lf\n", (1/l)-(1/(r+1)));

        }

return 0;

}