μ is the dipole moment.
The formula to calculate the μ is
μ=e.d , where "e" is the charge of the electron and "d" is the bond legnth 1 Ao
μcal=4.8×10−10e.s.u.×10−8cm=4.8×10−18esu.cm=4.8 D.
% of covalent character = μobsμcal×100
∴ % ionic character =2.44.8×100=50%
∴ % co-valent character = 50%