Vintage mechanical calculator - photo

[Toolmaker51]

Friden maybe, Burroughs was my impression with that little ten-key off the side.
Either way no match for more elegant and compact Comptometer.
https://en.wikipedia.org/wiki/Comptometer

This wikipedia photo identical to what my Aunt used, tallying AR's/AP's well into the full size desk electronic calculator era. Worked there 50+ years, retired and took The Comptometer home and did a little home business with it. It has been serviced but NEVER required repairs, used 5 [and probably a few 6] week days; by her only.
This machine, despite all the keys can outrun another skilled operator on a digital. I think the trick lies in dual numbered keys, instead of separate = + - % X /.
Due that operational design, requirement is better than average mathematics skills, to enact proper sequences.