how to calculate dipole moment of CH2CL2 ,CHCL3,CCL4 ?

Example Given below Shows how the Dipole moment of molecule is calculated after finding the bond dipoles.

Similarily dipole moments of CHCl3, CH2Cl2 and CH3Cl is calculated. But dipole moment of CCl4 is 0 because the vector sum of dipoles formed in CCl4 is zero.