try putting a file with a name where the first 6 characters are 246.56 inside the same directory you run the script from.
oh, nevermind, I see, you want to see how many files there are that match, and not get an error when the number is 0?
First, I think maybe you should be using wc -w, not -l
Second, I don't know, I don't know that much. But I'll try to think of something and come back if noone else does.