My apologies for revising the Topic Title with incorrect text. Your OP seemed to indicate you were trying to replace month name, but now with you last post I see you are simply look to replace any arbitrary text with a number.
So, I have revised the Topic Title again. Feel free to change if this does not accurately reflect your request.
Now that you have clarified your objective, I can provide a better solution. I have moved my prior post to a new topic. I'll post back soon with another solution.
Meanwhile, Please read:
Tip: How Do I Get The Best Answer in the Shortest Time?