I don't think it's possible to make a float number in script. I think it only supports integers. So you need to trick with integers and string texts. Ofc if you don't want to read the value from your settings, then simply write the value in the text, but I suspect you want to read the val from confs.
You can try the following (.@x = rate):
announce "The current base rate is: "+ .@x/100 +"."+ .@x-((.@x/100)*100),0;
(if the script does the flooring right after the division, then this should return first the integer part, then after the point the rest)