The North Korean government has imposed a surprise revaluation which changes the face value of the national currency, the 'won', to one hundredth of its previous value.
People will have to exchange, for example, each of their old 100 won notes for a single new 1 won note in return.
The shops are due to knock two zeros off their prices, so that those who have been keeping to the government's strict rules should, in theory, not lose out.
However, there is a catch: North Koreans can only exchange about $60 dollars' worth, based on the unofficial black market exchange rate.
So anyone with savings under the mattress worth more than $60 has lost it.
Marcus Noland is Deputy Director of the Washington-based Peterson Institute for International Economics. He is an expert on North Korea.
Those who have lost their life savings because of the move are said to be showing a rare display of anger at the dictatorship of Kim Jong-il.
There have been reports of people setting fire to piles of old won notes.
Tim Peters is the founder of Helping Hands Korea, a Christian non-governmental organisation in South Korea, which works with North Korean refugees.
First broadcast 4 December 2009
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