as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
calculate the number of years needed to double your money at 5% annual interest.
user
according to the 'rule of 72', we can divide 72 by the annual interest rate (as a percentage) to get the number of years it takes for an investment to double. 
72/6 = 14.4 
therefore the time it would take to double your money would be 14.4 years.
assistant