Hi Maky,
It is called round-off error. Anytime you are printing float or double values
you should format the results if it is important to you. Look at:
java.text.DecimalFormat
For example:
DecimalFormat df = new DecimalFormat( "#.00" );
System.out.prnitln( df.format( y ) );
will make your output look consistent.
Regards,
Manfred.