They worked just fine. Banks tended to close early in the day (like around 3:00) so that the bookkeepers could catch up on the paperwork (hence the saying "he works banker's hours," meaning he doesn't work much each day); companies called clearinghouses sorted paper checks and sent them to the appropriate banks. Not quite as efficient as today, but there was a system that worked.

There were numerous systems like accounting machines, adding machines, calculators and pen and paper.

Some of those calculator accounting machines were efficient for the time and while some could do numerous calculations at the same they still required the staff to do the inputs. I recall I would process a batch of invoices and put them into an early spreadsheet a large wide folded print-out. Another staff member would them input them into another machine for other analyses and a computer now can do the whole thing faster

Chetak

the same as they do now it's just quicker when it suits them it took 5 days for a cheque to clear 200 years ago it still does but they charge more

By employing hundreds of clerks who could add and subtract and write the results in ledgers.

With paper