Auto Number +1 from text, if duplicate text not increase

Hi All,

Can help me about formula in column B want result generate Number +1 from column A if Name same / duplicate not increase number.
[TABLE="class: grid, width: 500"]

[tr]

[td]

Name

[/td]

[td]

Number (Result)

[/td]

[/tr]

[tr]

[td]

a

[/td]

[td]

1

[/td]

[/tr]

[tr]

[td]

a

[/td]

[td]

1

[/td]

[/tr]

[tr]

[td]

a

[/td]

[td]

1

[/td]

[/tr]

[tr]

[td]

b

[/td]

[td]

2

[/td]

[/tr]

[tr]

[td]

c

[/td]

[td]

3

[/td]

[/tr]

[tr]

[td]

d

[/td]

[td]

4

[/td]

[/tr]

[tr]

[td]

d

[/td]

[td]

4

[/td]

[/tr]

[tr]

[td]

e

[/td]

[td]

5

[/td]

[/tr]

[tr]

[td]

f

[/td]

[td]

6

[/td]

[/tr]

[tr]

[td]

g

[/td]

[td]

7

[/td]

[/tr]

[/TABLE]

Thanks - John

Re: Auto Number +1 from text, if duplicate text not increase

Quote from AliGW;774431

Type the first result into B1 (1), then in B2 copied down:

=IF(COUNTIF($A$1:A2,A2)>1,B1,B1+1)

Thanks ALiGW it's work great.