If Aufbau's rule is not followed and electron filling  is done shell after shell, then number or unpaired  electrons present. in copper will be:

The number of unpaired electrons present in copper would be only one.

The Aufbau's principle states that copper has two valence electrons because its 4s orbitals are filled before its 3d ones. However, if the principle is not followed, copper's 4s orbital's single electron will be shared with the 3d orbital in order to make it fully filled, leaving copper with just one valence electron.