Double your money - Rule of 72 Approximately how long will it take to double your money if you get an annual return of 3.5%,7.2%, or 9.5% on your investment? Approcmately how long wil a take to double your money if you get a 3.5% annuai retum on your investrnent? yoars (Round to two decimal places) Approximatoly how long will it take to double your money if you get a 7.2% annual return on your irvestment? years (Round to two decimal places.) Approximately how lang will it take to double your money if you get a 0.5% annial retum on your imvestment? years (Round to two decimal places.)