I have a chart based on data where the label at the top of each column
of data is a number. I want the name of the data series to be this
number followed by a colon and a '1'. I can do this in a cell with the
formula

=LED!$C$2&":1"

But when I try to enter this in the name for the series it gives me an
error. I have also tried formulas using TEXT() and CONCATENATE() and
get the same error. Is this not possible in a series name entry?

I am also trying to get the same display in the column headers. Is
there a way to format a number with up to two decimal places if the
digits are not zero and not display the decimal point if the number is
an integer? I can do this with a complicated text function, but I
don't see how to do it with formatting controls.