Keyword Analysis & Research: what do square brackets mean in math

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
what do square brackets mean in math	0.14	1	5367	25	36
what	1.49	0.4	2133	40	4
do	0.01	1	5802	53	2
square	1.99	0.3	4096	13	6
brackets	1.22	0.2	9244	41	8
mean	0.97	0.9	6138	39	4
in	1.12	0.2	1978	4	2
math	0.77	0.5	4689	15	4

Keyword	CPC	PCC	Volume	Score
what do square brackets mean in math	1.52	1	8331	55