Excel is going to try to recognize your system as numbers where 1.11 is less
than 1.2.
You could force thenm to be text, and have a special list for sorting, but
numbers as text have there own issues.

Could you enter the data as 1.01,1.02, etc This would sort.
Can you have a helper column to do the true sorting from.
with
=if(mod(round(A1*100,0),10)=0,Floor(A1,1)+mod(A1,1 )/10,A1)
copy this down to the end of your data

"Colleen" wrote:

I need for Excel to sort by the numbering system 1.1, 1.2, 1.3, 1.4, 1.5,
1.6, 1.7, 1.8, 1.9, 1.10, 1.11 and so on. It does not seem to recognise this
numebring.

I have tried to creat it under the custom button but it still doens't work -
any ideas would be appreciated.