I'd probably use the middle column numbers... but, round them out to the appropriate "modern day" apertures.
For example, on the lens is the figure 48. If you look at the left hand column in the scale, it looks to correspond to 21.9, which, rounded off, is equivalent to f22.
The figure 24 looks to correspond to 15.5, which, rounded off, is equivalent to f16.
Take the lens out and take some pictures premised on the above and see what turns out.
Caveat: This is just my best guess since I've not used one of these lenses before. But, I'll bet Jim Galli has and, perhaps, he'll jump in with some thoughts.
Good luck.
Cheers