How long will it take for Ron's $37,353 investment to double if he expects 9% returns?
A)5 years
B)8 years
C)9 years
D)9)5 years
E)10 years

Question

Quizplus · Accepted Answer

To calculate this answer mentally, use the Rule of 72.
Divide 72 by the rate of growth. In this example, Ron's money would double in 8 years (72/9). The rule of 72 is a quick mental calculation tool that provides an estimate of how long it would take an investment to grow double.
Key Takeaway: For a few days, practice this every time you see a growth rate in the news paper or at work.

How Long Will It Take for Ron's $37,353 Investment to Double