Update README.md

Author: Vaibhav-Vipin

BasicPythonScripts/Compound Interest/README.md

@@ -13,6 +13,11 @@
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 ## Detailed explanation :- 
   compound_interest.py is very simple program which helps a user to caculate CI/an yearly estimated interest & save their time. After knowing how many years they will be saving, their account balance, amount they want to invest, and yearly interest of the ivestment.
+  We know compound interest is when a bank pays interest on both the principal (the original amount of money)and the interest an account has already earned.
+  To calculate compound interest use the formula below. In the formula, A represents the final amount in the account after t years compounded 'n' times at interest rate 'r' with starting amount 'p' . 
+  <p align = "center">
+  <img src="./Images/formula_ci.png"/>
+  </p>
 
 ## Output:- 
   <p align = "center">