Use the attached formula.
exp = [log (total / principal) / n*years]
where "n" is compounding periods per year
exp = [log (7,194.66 / 2,978.41) / (365*21)
exp = log (
<span>
<span>
<span>
2.4156042989
</span>
</span>
</span>
) / 7,665
exp = log (
<span>
<span>
2.4156042989
</span>
</span>
) / 7,665
exp = 0.38302579382 / 7,665
exp =
<span>
<span>
<span>
0.00004997074935681670
</span>
</span>
</span>
rate = (10^exp -1)* n
rate = (10^<span>0.00004997074935681670 -1) * n
</span>rate = <span><span>(1.0001150685
</span>
-1) * 365
</span>rate = <span>(.0001150685) * 365</span>
rate =
<span>
<span>
<span>
0.0420000025
</span>
</span>
</span>
rate = <span>4.20000025
%
rate = 4.2 %
Yes, it's just that easy. LOL
</span>
