diff --git a/Solutions/Module4MortgageCalculatorChallengeSolution.py b/Solutions/Module4MortgageCalculatorChallengeSolution.py
index ddb9c28..8d6b4a9 100644
--- a/Solutions/Module4MortgageCalculatorChallengeSolution.py
+++ b/Solutions/Module4MortgageCalculatorChallengeSolution.py
@@ -1,4 +1,3 @@
-
 #Declare and initialize the variables
 monthlyPayment = 0
 loanAmount = 0
@@ -7,26 +6,26 @@
 loanDurationInYears = 0
 
 #Ask the user for the values needed to calculate the monthly payments
-strLoanAmount = input("How much money will you borrow? ")
-strInterestRate = input("What is the interest rate on the loan? ")
+strLoanAmount = input("How much money will you borrow?  ")
+strInterestRate = input("What is the interest rate on the loan? (ex 6%=.06)   ")
 strLoanDurationInYears = input("How many years will it take you to pay off the loan? " )
 
-#Convert the strings into floating numbers so we can use them in teh formula
+#Convert the strings into floating numbers so we can use them in the formula
 loanDurationInYears = float(strLoanDurationInYears)
-loanAmount = float(strLoanAmount)
-interestRate = float(strInterestRate)
+P = float(strLoanAmount)
+I = float(strInterestRate)/12
 
 #Since payments are once per month, number of payments is number of years for the loan * 12
-numberOfPayments = loanDurationInYears*12
+N = loanDurationInYears*12
+
 
 #Calculate the monthly payment based on the formula
-monthlyPayment = loanAmount * interestRate * (1+ interestRate) * numberOfPayments \
-    / ((1 + interestRate) * numberOfPayments -1)
+monthlyPayment = P *( I * (1+ I)**N / ((1 + I)**N -1))
 
 #provide the result to the user
 print("Your monthly payment will be " + str(monthlyPayment))
 
 #Extra credit
 print("Your monthly payment will be $%.2f" % monthlyPayment) 
-
+## for this example (Principle = 100,000, Interest = 6%, years = 15,  monthly payment = 843.86)