Imaginary Number  more ...  Imaginary Number A number that when
squared gives a negative result.  If you square a Real Number
you always get a positive, or zero, result. For example 2×2=4,
and (-2)×(-2)=4 as well.  So how can we square a number and get
a negative result? Because we "imagine" that we can.  The "unit"
imaginary numbers (the same as "1" for Real Numbers) is √(-1)
(the square root of minus one), and its symbol is i, or j.