1.0E+1f  =  1.0E+1f
1.0E+2f  =  1.0E+2f
1.0E+3f  =  1.0E+3f
......
......
1.0E+25f  =  1.0E+25f
1.0E+26f  =  1.0E+26f
1.0E+27f  =  1.0E+27f
1.0E+28f  =  9.999999E+27f   // Why!!?????

string str1 = (1.0E27f).ToString();  // str1 = "1E+27"
        string str2 = (1.0E28f).ToString();  // str2 = "9.999999E+27";
        string str3 = (1.0E29f).ToString();  // str3 = "1E+29"

0.9999998261528069050908803072e28f
0.9999999442119689768320106496e28f <- the nearest one
1.0000000622711310485731409920e28f

1.00000010011111100111000 * 2^93
1.00000010011111100111001 * 2^93
1.00000010011111100111010 * 2^93