Financial Mathematics:Magical Numbers 72,114 and 144

It is always a tedious job to calculate rate of return on various products to take investment decisions.

In financial mathematics there are certain magical numbers which would help you in calculating the rate of return for doubling,tripling or quadrupling or if rate of return is available it can help you to calculate time required to double, triple or quadruple your capital

Let us find out how :

Take an example of Mr.Doguna who has been advised by one of his agent that there is an investment opportunity whereby he can double his money in 8 years. Now Mr.Doguna wishes to calculate the rate of return of the same. 

What he need to do is just divide 72 by the no. of years. i.e. 72/8 = 9%. 

So the approximate rate of return would be 9%.Although it doesn't give an exact result but you can have a rough calculation by doing this.

Lets say Mr.Doguna got an rate of interest of 12% and now he wishes to calculate the time period required to double his amount then he need to divide 72 by rate of interest i.e.

72/12 = 6 years (approx.)

Similarly you can calculate period/rate to triple your money by dividing 114 by the available variable and to quadruple replace magical no.114 by 144. 

for example if you wish to triple your money in 12 years required rate of interest would be 114/12= 9.50%.

To quadruple your money in 16 years required rate of return would be 144/16 = 9%.

In above example if rate of return is available and you wish to calculate time period divide magical nos. by rate of return.

Hope, above nos, will help you to make certain calculations on your fingertip without depending on software, excel sheet or financial calculators to take informed decisions.