Is it possible to specify a formula that creates a custom numbering format.
For example, I want to set up a column that can do this:

1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11, etc.

I tried to do decimal addition, but that doesn't allow 1.10, 1.11, 1.12, etc.

Is there a way to do this using the standard features of Excel, or does
someone know the formula to program this?

Thanks.