Python Program - Compound Interest WITH Monthly Contributions/Deposit
by matt392 in Circuits > Software
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Python Program - Compound Interest WITH Monthly Contributions/Deposit
Program to calculate compound interest with monthly contribution at the end of the month.
Formula taken from TheCalculatorSite.com:
Compound interest for principal:
P(1+r/n)^(nt)
Future value of a series:
PMT × (((1 + r/n)^nt - 1) / (r/n))
Downloads
Get Data From User
Ask the user to put in the required data:
principalinput = input("Enter principal: ")
annualrateinput = input("Enter annual rate: ")
numberoftimescompoundedinput = input("Enter number of times that the interest is compounded per year: ") yearsinput = input("Time in years: ")
monthlycontributioninput = input("Enter monthly contribution amount: ")
Convert Data
Data is entered as a strings which must be converted into integers
# Convert entered input from strings into integers
principal = int(principalinput)
annualrate = (int(annualrateinput))/100
numberoftimescompounded = int(numberoftimescompoundedinput)
years = int(yearsinput)
monthlycontribution = int(monthlycontributioninput)
Calculate the Compound Interest Plus the Principal
First, calculate the compound interest plus the principal:
# calculate compound interest plus the principal
preliminarynumber = (1 + (annualrate/numberoftimescompounded))
# print ("Preliminary number:", preliminarynumber)
raisedtopower = (numberoftimescompounded * years)
# print ("Raised to power:", raisedtopower)
compoundinterestplusprincipal = principal * (preliminarynumber**raisedtopower)
print("The compound interest plus the principal is: ", compoundinterestplusprincipal)
Calculate the Future Value
Then calculate the future value with deposits
# Now calculate the future value with deposits made at the end of the period
# Using formula: Monthly Payment × ( ( ( (1 + r/n)^(nt) ) - 1 ) / (r/n) )
# r = annual interest rate
# n = number of compounds per period (usually in months)
# t = time the money is invested (usually in years)
oneplus = (1+(annualrate/numberoftimescompounded))
raisedtopower2 = ((numberoftimescompounded*years))
ratedividedbynumberoftimes = annualrate/numberoftimescompounded
halfdone = (((oneplus**raisedtopower2)-1)/ratedividedbynumberoftimes)
futurevaluewithdeposits = monthlycontribution*halfdone
print ("Future value with deposits: ",futurevaluewithdeposits)
totalamount = compoundinterestplusprincipal + futurevaluewithdeposits
print ("Total Amount:", totalamount)
Code
# Program to calculate compound interest with monthly contribution at end of month
# First calculate the compound interest for principal using formula: A = P (1 + r/n)**(nt)
# r = annual interest rate
# n = number of compounds per period (usually in months)
# t = time
principalinput = input("Enter principal: ")
annualrateinput = input("Enter annual rate: ")
numberoftimescompoundedinput = input("Enter number of times that the interest is compounded per year: ")
yearsinput = input("Time in years: ")
monthlycontributioninput = input("Enter monthly contribution amount: ")
# Convert entered input from strings into integers
principal = int(principalinput)
annualrate = (int(annualrateinput))/100
numberoftimescompounded = int(numberoftimescompoundedinput)
years = int(yearsinput)
monthlycontribution = int(monthlycontributioninput)
print ("The principal entered is: ", principal)
print ("The annual rate in decimal form is: ", annualrate)
print ("The number of times it will be compounded per year is: ", numberoftimescompounded)
print ("The number of years it will be compounded: ", years)
print ("The monthly contribution is: ", monthlycontribution)
# calculate compound interest plus the principal
preliminarynumber = (1 + (annualrate/numberoftimescompounded))
# print ("Preliminary number:", preliminarynumber)
raisedtopower = (numberoftimescompounded * years)
# print ("Raised to power:", raisedtopower)
compoundinterestplusprincipal = principal * (preliminarynumber**raisedtopower)
print("The compound interest plus the principal is: ", compoundinterestplusprincipal)
# Now calculate the future value with deposits made at the end of the period
# Using formula: Monthly Payment × ( ( ( (1 + r/n)^(nt) ) - 1 ) / (r/n) )
# r = annual interest rate
# n = number of compounds per period (usually in months)
# t = time the money is invested (usually in years)
oneplus = (1+(annualrate/numberoftimescompounded))
raisedtopower2 = ((numberoftimescompounded*years))
ratedividedbynumberoftimes = annualrate/numberoftimescompounded
halfdone = (((oneplus**raisedtopower2)-1)/ratedividedbynumberoftimes)
futurevaluewithdeposits = monthlycontribution*halfdone
print ("Future value with deposits: ",futurevaluewithdeposits)
totalamount = compoundinterestplusprincipal + futurevaluewithdeposits
print ("Total Amount:", totalamount)