I think the test is not passing because your calculator isn’t quite behaving correctly.
If you click ‘AC’ or ‘C’ you have a zero in the ‘answer’ display. If you then enter ‘0’ however, the zero disappears from the display. This could be what is causing that test to fail. The zero also disappears from both displays if you enter a decimal point (e.g. trying to enter the number 0.03, the display removes the integer 0 leaving only .03).
Thanks! I checked again that part of the code and I found the mistake! thanks again!