In your print statement ... (berkshire_return/100)*(1/10)-1:.4f ... gives the annualised return (assuming start with 100 and 10 years). That brings you into al

In your print statement ... (berkshire_return/100)*(1/10)-1:.4f ... gives the annualised return (assuming start with 100 and 10 years). That brings you into alignment with the article.