Question

How to find no of years in compound interest?

Answer 1

The general technique when the nn is in the exponent is to use loglog and then use the rule log(x)n=nlog(x)log⁡(x)n=nlog⁡(x).

50005000/2500log(5000/2500)log(5000/2500)n=2500(1.035)n=(1.035)n=log((1.035)n)=nlog(1.035)=log(5000/2500)log(1.035)≈20.155000=2500(1.035)n5000/2500=(1.035)nlog⁡(5000/2500)=log⁡((1.035)n)log⁡(5000/2500)=nlog⁡(1.035)n=log⁡(5000/2500)log⁡(1.035)≈20.15

A quick and dirty way to get the number of years to double your money is to use the rule of 72