read file and split the lines into 7 separate files

def split_to_7_files(filename):
    # read file
    f = open(filename, "r")
    lines = f.readlines()
    f.close()
    # split the lines into 7 separate files
    n = len(lines)
    k = n // 7
    for i in range(7):
        # create output filename
        fout_name = filename.split(".")[0] + "_" + str(i) + "." + filename.split(".")[1]
        # write to file
        fout = open(fout_name, "w")
        for j in range(i*k, (i+1)*k):
            fout.write(lines[j])
        fout.close()

split_to_7_files("text.txt")