For the most part, all you should need to do is copy & paste the example from that document as-is, rather than trying to reconstruct the entire field yourself.
As for the output, maybe you should consider using logarithmic values for the output. That way the re-scaling is both progressive and automatic. To see how to do that in Word, check out the
Logarithms topic in my
Microsoft Word Field Maths Tutorial:
https://www.msofficeforums.com/word/...-tutorial.html. Otherwise, all you need to add is a single IF test that divides the merged value by a given constant if it exceeds 10.