#include <stdlib.h>
#include <stdio.h>

int main()
{
    int cnt = 0;
    int n = 0;
    int k = 0;

    double **bin = (double **) malloc(sizeof(double *) * (2001));

    for (int i = 0; i < 2001; i++)
        bin[i] = (double *) malloc(sizeof(double) * (2001));

    for (int i = 0; i < 2001; i++)
    {
        bin[i][0] = bin[i][i] = 1;
        for (int j = 1; j < i; j++)
            bin[i][j] = bin[i - 1][j - 1] + bin[i - 1][j];
    }

    scanf("%d", &cnt);

    for (int i = 0; i < cnt; i++)
    {
        scanf("%d %d", &n, &k);
        printf("%0.10g\n", bin[n][k]);
    }

    return 0;
}