Here we will show you how to calculate how long it will take to double your money with 3.905 percent interest.
Basically, you want to know how far into the future until your present investment, with 3.905 percent interest, will be twice as much.
The formula to calculate this is:
n = ln(2)/r
Where n is time, r is percent and ln(2) is 0.69314718056 per our calculator.
Therefore, the answer is simply
0.69314718056 / 0.03905 which is
17.75 years
We assumed the 3.905 percent was the yearly rate. If the 3.905 percent is the monthly rate, then simply
replace years with months above.
You may have heard of "the rule of 72", where you use 72 and 3.905 instead of 0.69314718056 and 0.03905 as
follows: 72/3.905 = 18.44 years.
The rule of 72 does not give the exact answer, as our answer did above, but it is good to know if you
only need an approximate answer and you don't have access to Research Maniacs.
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