@@ -1,3 +1,34 @@
 # mortgage.py
 #
 # Exercise 1.7
+principal = 500000.0
+rate = 0.05
+payment = 2684.11
+total_paid = 0.0
+extra_payment_start_month = 60
+extra_payment_end_month = 108
+extra_payment = 1000
+month_counter = 0
+
+while principal > 0:
+    month_counter += 1
+    if month_counter == extra_payment_start_month:
+        payment += extra_payment
+    elif month_counter == extra_payment_end_month + 1:
+        payment -= extra_payment
+
+    principal = principal * (1 + rate / 12)
+
+    if principal > payment:
+        total_paid += payment
+        principal -= payment
+    else:
+        total_paid += principal
+        principal = 0
+
+    print(f"Month #{month_counter:4d} | Total paid: {total_paid:0.2f} | Principal: {principal:0.2f}")
+
+
+print(f'\n=============================')
+print('Total paid', round(total_paid, 2))
+print('Months', month_counter)