We revisited the result |zw| = |z||w| and Arg(zw) = Arg(z) + Arg(w) and de Moivre's Theorem to see how they also implied that |z/w| = |z|/|w| and Arg(z/w) = Arg(z) - Arg(w). We used these results to make some calculations. We looked at the factorisation of the polynomial x^4 - 1.