According to the Aufbau principle, electron enters into the lowest energy level (orbital), before entering into a higher energy level. Hence, according to this principle, the electronic configuration of \\\\(Ca^{20}\\\\) is \\\\(1s^22s^22p^63s^23p^64s^2\\\\), as differentiating electron enters into the s-orbital, \\\\(Ca\\\\) belongs to s-block. If we don't follow the Aufbau rule, the electronic configuration of \\\\(Ca^{20}\\\\) would be \\\\(1s^22s^22p^63s^23p^63d^2\\\\).Here, the differentiating electron is entering in the d orbital, so it would belong to the d-block element.