Simplify $(1-3i) + (2-i) + (2+i) + (1+3i)$.
Opening parenthesis for only addition never hurts: \(1 - 3i + 2-i+2+i+1+3i\)
One can treat \(i=\sqrt{-1}\) as a variable, and combine like terms normally: \(1+2+2+1-3i+3i-i+i=6\)
