Keyword Analysis & Research: why is it called a number 2 pencil

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
why is it called a number 2 pencil	0.29	0.4	6714	40	34
why	1.94	0.2	205	60	3
is	0.28	0.6	4795	33	2
it	0.51	0.6	9773	80	2
called	1.52	0.4	84	98	6
a	0.59	0.5	4449	2	1
number	0.65	0.6	7645	49	6
2	0.28	0.1	6639	19	1
pencil	0.73	0.4	2000	51	6

Keyword	CPC	PCC	Volume	Score
why is it called a number 2 pencil	0.41	0.3	6317	50