The irrational number I researched is “e” or Euler’s number. It is equal to about 2.71828182846... and is known to over 1 trillion digits of accuracy. This number was found by a mathematician named Leonhard Euler in the 1700’s  and he calculated this number to 23 decimal places and is also the base of natural logarithms.  It can be calculated as the sum of an infinite series but is more commonly used in the study of compound interest. Compound interest is interest on interest and is the result of reinvesting interest. This type of interest grows at a faster rate than simple interest which is interest only calculated on the principal amount. There are many ways to calculate “e” but none of them give an exact answer as it is irrational. One method is to find the value of e is: 1/0! + 1/1! + 1/2! + 1/3! + 1/4! + 1/5! + 1/6! + 1/7! + … which results in 2.71828182846...

Sources:

http://qz.com/362732/the-other-irrational-numbers-we-could-celebrate-instead-of-pi/

http://www.mathsisfun.com/numbers/e-eulers-number.html

https://en.wikipedia.org/wiki/Compound_interest

https://plus.maths.org/content/where-does-e-come-and-what-does-it-do