You can use the “power()” function to calculate an exponent in a formula field. For example, to calculate simple interest with the following formula :
(Principle * (1 + 0.08 / 365) + fee) ^ (Todaysdate - Issue_Date)
use the power() function as given below:
(Principle * (1 + 0.08 / 365) + fee).power(Todaysdate - Issue_Date))