Second instance of a money value print returns a value different than the first print with Python

I’m working on a program that is a simulation of an order form/receipt. First, the program prints an invoice, then later prints a receipt based on which payment schedule the user selects (1-4 years) My problem is that I can’t find a way to get the invoice and receipt to print the same monthly payment. This is the code used for the invoice:

for NumYears in range (0, 4):
    NumYears += 1
    NumPayment = NumYears * 12
    FinanceFee = 39.99 * NumYears
    TotPrice = TotSalesPrice + FinanceFee
    MonPay = TotPrice / 12

it prints as:

# Years   # Payments   Financing Fee   Total Price   Monthly Payment
----------------------------------------------------------------------
    1         12             $39.99       $9,914.99            $826.25
    2         24             $79.98       $9,954.98            $829.58
    3         36            $119.97       $9,994.97            $832.91
    4         48            $159.96      $10,034.96            $836.25
---------------------------------------------------------------------

The second part of the code, for the receipt is:

MonPay1 = TotPrice / 12
MonPay2 = (TotPrice / 12) * 2
MonPay3 = (TotPrice / 12) * 3
MonPay4 = (TotPrice / 12) * 4

while True:
    if PayMethod == "1":
        print("Terms: 1       Total Payments: 12")
        break
    elif PayMethod == "2":
        print("Terms: 2       Total Payments: 24")
        break
    elif PayMethod == "3":
        print("Terms: 3       Total Payments: 36")
        break
    elif PayMethod == "4":
        print("Terms: 4       Total Payments: 48")
        break


while True:

    if PayMethod == "1":
        print(f"Monthly payment:       {MonPay1Dsp:>10s}")
        break
    elif PayMethod == "2":
        print(f"Monthly payment:       {MonPay2Dsp:>10s}")
        break
    elif PayMethod == "3":
        print(f"Monthly payment:       {MonPay3Dsp:>10s}")
        break
    elif PayMethod == "4":
        print(f"Monthly payment:       {MonPay4Dsp:>10s}")
        break
    else:
        break

it prints as:

    Sale price:             $5,000.00
    Trade Allowance:        $1,000.00
    Price after Trade:      $4,000.00
                            ----------
    HST:                      $750.00
    License Fee:               $75.00
    Transfer Fee:           $5,050.00
                            ----------
    Total Sales Cost:      $10,034.96
----------------------------------
Terms: 1       Total Payments: 12
Monthly payment:          $836.25
First payment date:   31-Jan-2022

What can I do to fix the discrepancy?

EDIT: Adding in all the calculations. I’ve gone over them a few times and can’t find the error. Maybe I’ve just been looking at it too long… I don’t know.

HST_FEE = .15
TRANS_FEE_LOW = 0.01
TRANS_FEE_HIGH = 0.026
LISC_FEE_LOW = 75.00
LISC_FEE_HIGH = 165.00

PriceAfterTrade = SellPrice - AmtTradeIn
Taxes = HST_FEE * SellPrice

if SellPrice <= 5000.00:
    LiscFee = LISC_FEE_LOW
else:
    LiscFee = LISC_FEE_HIGH
if SellPrice >= 20000.00:
    TransFee = (TRANS_FEE_HIGH * SellPrice) + SellPrice
else:
    TransFee = (TRANS_FEE_LOW * SellPrice) + SellPrice


TotSalesPrice = PriceAfterTrade + Taxes + LiscFee + TransFee

Answer

The error in your code just hit me: your calculations for MonPay1, … all used TotPrice, with the value set at the end of the invoice loop, so the value for 4 years!

Here is the code I rewrote (based on my understanding of your different values). You’ll probably have to tweak some things to fit your needs.

# Data

SellPrice = 5000

AmtTradeIn = 1000

HST_FEE = .15
TRANS_FEE_LOW = 0.01
TRANS_FEE_HIGH = 0.026
LISC_FEE_LOW = 75.00
LISC_FEE_HIGH = 165.00

PriceAfterTrade = SellPrice - AmtTradeIn
Taxes = HST_FEE * SellPrice

if SellPrice <= 5000.00:
    LiscFee = LISC_FEE_LOW
else:
    LiscFee = LISC_FEE_HIGH
if SellPrice >= 20000.00:
    TransFee = (TRANS_FEE_HIGH * SellPrice) + SellPrice
else:
    TransFee = (TRANS_FEE_LOW * SellPrice) + SellPrice


TotSalesPrice = PriceAfterTrade + Taxes + LiscFee + TransFee

print(TotSalesPrice)


# Code for invoice

MonPay=[0]

for NumYears in range (1, 5):
    NumPayment = NumYears * 12
    FinanceFee = 39.99 * NumYears
    TotPrice = TotSalesPrice + FinanceFee
    MonPay.append(TotPrice / 12 / NumYears)
    print(MonPay[NumYears])
    

# Code for receipt

PayMethod = "1" #This is an example for testing purpose

print("Terms: " + PayMethod + "       Total Payments: "+str(12*int(PayMethod)))
print(f"Monthly payment:       ${MonPay[int(PayMethod)]}")