Keyword Analysis & Research: why are they called imaginary numbers

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
why are they called imaginary numbers	0.24	0.5	9394	8	37
why	0.06	0.5	2489	47	3
are	0.25	0.4	3407	3	3
they	1.81	0.3	5893	62	4
called	1.05	0.7	8750	8	6
imaginary	1.35	0.7	4278	35	9
numbers	1.79	0.3	644	20	7

Keyword	CPC	PCC	Volume	Score
why are they called imaginary numbers	0.05	0.8	6487	16