=mod(B1-1,20)+1

or you can use the row number

=mod(row(B1)-1,20)+1


"Ben" wrote:

Hi all,

I', regular reviewer of the Excel discussion groups and found it invaluable.
I can usually find the answers i need but not to this example(so thanks in
advance). I'm working with Excel 2003, and have a list that i want to expand
by a certain number. For example I want the set number in column A to
increase in groups of 20 assets:
A B
Set Asset
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
2 21

So asset 21-40 will be set 2, asset 41-60 will be set 3 etc. I have 3000
assets(so far) and don't want to go through manually. This should be easy to
solve but I can't figure it out.