Compute!
The SBRC brain trust has developed a unitaware language called sbrclang designed specifically to compute running paces, times, and distances. For example:

8:00 mi * 1:00:00
Computes how far you have run in 1 hour at a pace of 8 minutes per mile. 
8:00 mi > 10 km
Solves for time and computes the amount time it takes to run a 10K at a pace of 8 minutes per mile. 
8:00 mi > 1 mi @ 10 km
Prints a pace chart at increments of 1 mile to a distance of 10K at a pace of 8 minutes per mile.
It’s not rocket science. See examples below and sbrclang documentation for more details.