Why do some countries go through with a currency redenomination and how effective is it, if at all?

Question

For example, Mauritania changed its currency to the “New Ouguiya” with a rate of 1:10 compared to the old one. Another more severe example is White Rossia, with two changes ending up with 1;10,000,000 compared to their first Rouble.

In: 2

Answer 1

I am not asking about anything that’s been happening in the last month.