import math

Function to calculate the future value of an investment based on interest type

def investment_calculator(): """ This function calculates the total amount after a given number of years based on an initial deposit, interest rate, and the type of interest (simple or compound). The user is prompted for the necessary inputs, and the function will output the total amount at the end of the investment period. """

# Input: Get the deposit amount, interest rate, and number of years from the user
deposit = float(input("Enter the amount of money you are depositing: "))
rate = float(input("Enter the interest rate (as a percentage): "))
years = int(input("Enter the number of years you plan on investing: "))

# Convert the interest rate from percentage to decimal for calculation
rate /= 100

# Ask the user if they want simple or compound interest
interest_type = input("Do you want simple or compound interest? ").lower()

# Calculate total amount based on the interest type selected
if interest_type == "simple":
    # Simple interest formula: A = P(1 + rt)
    total_amount = deposit * (1 + rate * years)
elif interest_type == "compound":
    # Compound interest formula: A = P(1 + r)^t
    total_amount = deposit * math.pow((1 + rate), years)
else:
    # If the user enters an invalid option, exit the function
    print("Invalid interest type entered.")
    return

# Output: Display the total amount after the investment period
print("Total amount after {} years: {:.2f}".format(years, total_amount))

Function to calculate monthly bond repayments (mortgage)

def bond_calculator(): """ This function calculates the monthly repayment on a bond (home loan). The user is asked for the present value of the house, the interest rate, and the number of months for repayment. The function outputs the monthly repayment amount based on this information. """

# Input: Get the present value of the house, interest rate, and repayment period (in months)
present_value = float(input("Enter the present value of the house: "))
rate = float(input("Enter the interest rate (as a percentage): "))
months = int(input("Enter the number of months for repayment: "))

# Convert the annual interest rate to a monthly rate (as a decimal)
rate /= 100
monthly_rate = rate / 12

# Bond repayment formula: 
# Monthly repayment = [r * P] / [1 - (1 + r)^(-n)]
# where P is the present value, r is the monthly interest rate, and n is the number of months
repayment = (monthly_rate * present_value) / (1 - math.pow((1 + monthly_rate), -months))

# Output: Display the monthly repayment amount
print("Monthly repayment amount: {:.2f}".format(repayment))

Main function to drive the financial calculator

def main(): """ This is the main function of the financial calculator. It presents the user with a menu to choose between calculating investment returns or bond repayments, and then calls the corresponding function based on the user's choice. """

# Display the menu to the user
print("Welcome to the financial calculator!")
print("Menu:")
print("1. Investment - to calculate the amount of interest you'll earn on your investment")
print("2. Bond - to calculate the amount you'll have to pay on a home loan")

# Get the user's option and convert to lowercase for easier matching
option = input("Enter either 'investment' or 'bond' from the menu above to proceed: ").lower()

# Call the appropriate function based on the user's choice
if option == "investment":
    investment_calculator()  # Calls the investment calculator
elif option == "bond":
    bond_calculator()  # Calls the bond calculator
else:
    # If an invalid option is selected, display an error message
    print("Invalid option selected.")

Ensure the main function runs when the script is executed

if name == "main": main()

OlonaMashalaba / Github