import sys

def main():
    max_n = 10**5
    sum_albedo = [0.0] * (max_n + 1)
    for i in range(2, max_n + 1):
        sum_albedo[i] = sum_albedo[i - 1] + 1.0 / (i ** 2)
    
    input_data = sys.stdin.read().split()
    T = int(input_data[0])
    results = []
    for i in range(1, T + 1):
        N = int(input_data[i])
        s = sum_albedo[N]
        if s == int(s):
            results.append(str(int(s)))
        else:
            results.append("{0:.10f}".format(s))
    
    print('\n'.join(results))

if __name__ == '__main__':
    main()