Hi bssol and welcome to the forum

THis is probably way too simple for what you want, but have you tried this? Assuming the number that you want to automatically change is in A1, and the number you want to use to make that number change is in B1...
in A1 put =B1

you can upload your file here...
To attach a file to your post,
click advanced (next to quick post),
scroll down until you see "manage file",
click that and select "add files" (top right corner).
click "select files" find your file, click "open" click "upload" click 'done" bottom right. click "submit reply"

Once the upload is completed the file name will appear below the input boxes in this window.
You can then close the window to return to the new post screen.