you can use framestack to find out what they call the frame, then you can use Lua GetText from that frame
Then you can search the text for : and = and extract that text part. I don't know if it's random weather they use - + * / etc. If they do you just make 4 if statements and make it -, +, * or / based on what your search returns.
Make it calculate the two numbers on each side of the math symbol.
Voila, everything done in-game without second hand software, should be pretty easy to do.