Trim dynamic string

[#1]

I have a string which can be in the form of

1.1.5 or 16.25.7 or 100.444.111

I don't want anything after the 2nd decimal inclusive.

meaning expected output for the above example is

1.1, 16.25 and 100.444

I cant use left() because I don't know the exact format  which can be any of the above 3 formats. thank you

[jonathandienst]

This will return everything up to (and not including) the second period:

=Left(yourString, Index(yourString, '.', 2) - 1)