I used those, and several other versions of the currency, each defined as 1000 of the previous unit.  IIRC, at one point inflation got to 40% per month [ sic ].

But guess what, the economy kept working in spite of that.  badly, of course, but it did.  Sorry if that disappoints some, but civilization did not collapse.

And people did not get utterly ruined.  No sane person "invests" in cash; when the inflation gets too high, banks will offer inflation-corrected savings and investment funds, that allow fast deposit and withdrawal at any time.

Inflation, like salt on food, is good in small doses, disastrous otherwise.  It must be just big enough to dissuade people from hoarding the currency.  Inflation of 5% per year requires adjustments in salaries and prices, each year or every 6 months, and must be explicitly taken into account in planning or contracts spanning many months.  Beyond that, inflation begins to be a real pain: prices and salaries have to be adjusted all the time, people must rush to invest the salary, etc.