Doing math on the content of unique counts

(The following is a little contrived, but is a simplification of what I'm really after. Hopefully it didn't loose meaning when I abstracted the content, but man: it was really messy to read)

A. I have a field, Foo. I want to calculate the value of unique Foo per hour.

Create visualization, Bar, with Aggregation=Unique Count on that field, over an absolute range 07:00 - 08:00 and things are looking good.

So far, so good.

B. The Wrinkle: I want the sum of Foos per hour across the day.

value - time
38 - 07:00 - 08:00
46 - 08:00 - 09:00
80 - 09:00 - 10:00

Equals 164 for 3 hours.

Now, I could tell the marketing guys to break out their calculators, but I'm really hoping I can coerce kibana into doing arithmetic on the contents of unique counts ...

Could you use two visualizations - one with the data table broken out by hour, one with a single sum metric - on the same dashboard?

Let me try that. I think a problem I had yesterday was that the math didn't work out but .. that was yesterday.