How is the ROI time calculated Rule 72

Hey, guys how many of us have tried to find spreadsheets and formulas to use when investing in an asset like crypto or even stock or when we just try to save money in a bank account and want to calculate the amount of time we will need to double our money? Well, I will assume the majority. I just stumbled on a really simple way to calculate with a simple calculator the X amount of time you need to double your investment. The simple rule of 72
The rule is really simple you divide the number 72 by the interest or return an example if we had the same interests rates as last year's 0.1% we would need = 72 /0.1 = 720 years
With interest rates at 4%
X = 72 / 4 = 18 years
And if you are asking if is it compounding the answer is yes the results are in only by compounding interest since it can only be used for exponential growth 📈
There is also a formula you can use to calculate the halving of your money.
The rule of 70
You divide 70 by the number of the inflation and the result is how many years it will take for your money to lose half of its value.
ExampleI will use the desired inflation numbers = 70 / 2 = 35 years
So it will take your money 35 years to lose half of its value.
Since I live in Greece I will use our yearly inflation of 10%
X = 70 / 10 = 10 years
My money will lose half its value in 10 years. Interesting
I found that formula fun and experimented with different numbers a lot sometimes simple things like that can give a great perspective on a future investment without the need for complex formulas.

https://www.investopedia.com/terms/r/ruleof72.asp