---
id: 6a22d77ddf034bc4e35b1d55
title: "Challenge 348: Loan Calculator"
challengeType: 29
dashedName: challenge-348
---

# --description--

Given a loan amount, annual interest rate percentage, and fixed monthly payment, return an array of remaining balances after each monthly payment until the loan is paid off.

- Each month, interest is calculated on the remaining balance using the monthly interest rate: `(annual rate / 100) / 12`, then the monthly payment is subtracted.
- Return each remaining balance rounded to the nearest dollar.
- Include the loan amount in the returned array. The first element in the array will always be the loan amount, and the last element of the array will always be 0.

# --hints--

`get_loan_schedule(1000, 0, 200)` should return `[1000, 800, 600, 400, 200, 0]`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_loan_schedule(1000, 0, 200), [1000, 800, 600, 400, 200, 0])`)
}})
```

`get_loan_schedule(1000, 5, 200)` should return `[1000, 804, 608, 410, 212, 13, 0]`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_loan_schedule(1000, 5, 200), [1000, 804, 608, 410, 212, 13, 0])`)
}})
```

`get_loan_schedule(10, 50, 1)` should return `[10, 9, 9, 8, 8, 7, 6, 5, 5, 4, 3, 2, 1, 0, 0]`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_loan_schedule(10, 50, 1), [10, 9, 9, 8, 8, 7, 6, 5, 5, 4, 3, 2, 1, 0, 0])`)
}})
```

`get_loan_schedule(5500, 8, 400)` should return `[5500, 5137, 4771, 4403, 4032, 3659, 3283, 2905, 2525, 2141, 1756, 1367, 977, 583, 187, 0]`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_loan_schedule(5500, 8, 400), [5500, 5137, 4771, 4403, 4032, 3659, 3283, 2905, 2525, 2141, 1756, 1367, 977, 583, 187, 0])`)
}})
```

`get_loan_schedule(50000, 5.2, 1650)` should return `[50000, 48567, 47127, 45681, 44229, 42771, 41306, 39835, 38358, 36874, 35384, 33887, 32384, 30874, 29358, 27835, 26306, 24770, 23227, 21678, 20122, 18559, 16990, 15413, 13830, 12240, 10643, 9039, 7428, 5810, 4186, 2554, 915, 0]`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_loan_schedule(50000, 5.2, 1650), [50000, 48567, 47127, 45681, 44229, 42771, 41306, 39835, 38358, 36874, 35384, 33887, 32384, 30874, 29358, 27835, 26306, 24770, 23227, 21678, 20122, 18559, 16990, 15413, 13830, 12240, 10643, 9039, 7428, 5810, 4186, 2554, 915, 0])`)
}})
```

# --seed--

## --seed-contents--

```py
def get_loan_schedule(loan_amount, annual_rate, monthly_payment):

    return loan_amount
```

# --solutions--

```py
def get_loan_schedule(loan_amount, annual_rate, monthly_payment):
    monthly_rate = (annual_rate / 100) / 12
    balances = [loan_amount]
    balance = loan_amount

    while balance > 0:
        balance += balance * monthly_rate
        balance -= monthly_payment
        balances.append(round(max(balance, 0)))

    return balances
```