sequential number

[tony567]

A1: 1
A2: 2
A3: 5
A4: 6
A5: 7
A6: 8
A7: 10

How to get formula or maybe vba that will result an answered that number 3,4,9 is gone from that it should be data with sequential number

Thank you very much

 

[Sal Paradise]

Excel Workbook
	A	B	C
1	1		2
2	5		3
3	6		4
4	7		18
5	8		19
6	9		21
7	10		25
8	11		26
9	12		27
10	13		29
11	14
12	15
13	16
14	17
15	20
16	22
17	23
18	24
19	28
20	30
Sheet1

 

[tony567]

Formula... Great!
Thank you for the solution Sal

How about if the data is like:
A1: A1
A2: A2
A3: A5
A4: A6
A5: A8
A6: B3
A7: B5
A8: B6
A9: B10

How to get formula or maybe vba that will result an answered: A3,A4,A7,B1,B2,B4,B7,B8,B9

Thank you very much

 

[Sal Paradise]

That's a far more complex question and probably needs to be done with VBA. There is no easy way to determine which letter a certain value should be. For instance, 4 is missing -- is it A4 or B4? You need to clearly define your rules if you want it done that way.