z₁*z₂=(2/3+1/3i)(2i)=2/3*2i+1/3*2i²=4/3i-2/3
z₁:z₂=(2/3+1/3i)/(2i)=(2/3+1/3i)*i/(2i*i)=(2/3i-1/3)/(-2)=1/6-1/3i