Calculate the number of electron constituting 1 coulomb of charge
The charge on an electron is negative and it is -1.6⨯10-19 coulomb therefore, 1 C charge is carried by 1/ (-1.6⨯10-19) = 6.25 ⨯ 1018 electrons. Hence if 1 A current flows through a conductor, it implies that
6.25 ⨯ 1018 electrons pass per a second across the cross section of the conductor.