The calculation of complex numbers can be compared with the calculation of real numbers, and the real numbers can be operated. The key is to remember the formula of polynomial multiplication. ( 1)( 1-i)^2=( 1-i)( 1-i)= 1^2-2* 1*i+i^2= 1-2i- 1=-2i.(2)(7-6i)(-3i)=-3i * 7+(-3i)*(-6i)=-2 / kloc-0/i+ 18i^2=-2 1i- 18.(3)(3+4i)(-2-3i)=3*(-2)+3*(-3i)+4i*(-2)+4i*(-3i)=-6-9i-8i- 12i^2=-6- 17i+ 12 = 6- 17i .