<prompt> Human: Ive heard this before from many people but when I calculated, it seemed to be way off. Am I missing something that is throwing me off or is this a myth that has thrown me off?Assistant: What do you mean by money in the bank? For a normal bank account, no. Your money just sits there.You can put money in a high yield savings bank account, and those generate something like 1-2 returns per year. Not nothing, but not going to double your money. it would be 1.0210 , or 1.2. So your initial deposit increases by 20However, if what they mean by in the bank, is investing in the stockmarket, then yes. On average, the stockmarket returns 7 after inflation per year. So 1.0710, which comes out to 1.96, or 2. So yes, if your money is invested in the stock market in a reasonable way such as an index fund, see the sidebar, it will double roughly every 10 years or so on average.Human: Okay thank you, maybe I just misunderstood and took bank for the stock market investments  <response>: in the bank is a common idiom, so depending on where you heard it, they were either wrong or werent being literal.It basically means a sure thing 