On 1 July 2007 Ghana knocked four zeros off its currency. Ten thousand old cedis (¢) became one Ghana cedi (GH¢), and the pesewa came back as a hundredth of it.

Nothing about anyone’s wealth changed. A price of ¢20,000 became GH¢2, and a salary was divided by the same number. What changed was that ordinary transactions stopped needing five and six figures.

Older Ghanaians still occasionally quote the old money — “twenty thousand” for two cedis — the way people elsewhere quote pre-decimal currency. If a figure seems absurd by a factor of about ten thousand, this is why.

It matters for anyone reading data. Long-run series are usually expressed in today’s cedis all the way back, so the 1960s appear as fractions of a pesewa, and a multiple calculated across the change is arithmetic on two different units. Ghana also changed currency once before, in 1965, from the Ghanaian pound to the cedi.

Inflation and the cedi How to read Ghanaian statistics