I would like some math. I have a homebrewed rewards system where I get points for doing positive things. I would like to able to multiply the number of minutes logged to time based goals by their points value. So, I could be given half a point per minute of yoga and three points per minute of running. Then ifttt can send the points straight to my system and I can get more rewards 
I could also see it being useful for those with bucket goals fed by subgoals who want to get twice as much credit for harder tasks or activities.
I don’t need a whole calculator yet but an ability to multiply would be great and I’d use it heaps!