Percentage increase per year - in terms of fold

Question

If I say that the growth rate of real GDP was 3.3% per year. How do I know that over 127 years, the increase has been 64-fold?

Answer 1

If the GDP is increasing by $3.3\%$ per year, then each year, the GDP is multiplying by $1.033$.

$\text{GDP}\times1.033\times1.033\times1.033......=\text{GDP}\times1.033^{127}=\text{GDP}\times61.76$.

It seems to be more like 128 years, but you get the idea.