I haven't been able to come up with an appropriate formula for this
one, I hope someone can point me in the right direction.

I have a list of article numbers (the format is like 123.45.678). Next,
I have another list of article number ranges and its corresponding
product group (say from 123.45.601 to 123.45.700 is "Screws"). This
list has 3 columns: First article number in range/group, last article
number in range/group, and the name of the group.

Important: The ranges are not consistent, so in my example the next
product group up doesn't start with 123.45.701 but maybe with
124.00.000. Example:

Min_Max_Group
123.45.601 _123.45.700_Screws
124.00.000_124.99.999_Bolts
220.70.000_220.80.999_Casing

Now I need a formula that checks if an article number is = the minimum
value and <= the maximum value and then returns the group. (and, if
possible, to return "no group" if there is no range for that number,
like for 123.45.800)

So far I have been able to come up with a formula that checks if the
number is inbetween the min and max value (with sumproduct) and returns
TRUE or FALSE. But I can't figure out how to make the necessary lookup
in the Group column.

Thanks in advance
Andreas