Email Print Imaginary Number on 01 February 2016. Posted in Algebra An imaginary number has the symbol \(\large{ i }\) and when squared gives a negative number \(\large{ i^2 = -1}\) or \(\large{i = \sqrt{-1} }\) . Real \(\large{ -2^2=4 }\) Imaginary \(\large{ 2i^2=-4 }\)