Colin maxed out his credit card at $4,000 . the interest rate is 12.35% . using an online calculator, colin determines that if he stops using the card and pays $300 per month for the next 15 months, he will pay off his debt. how much interest will colin have paid when his credit card balance is $0 ?

So Colin is required to pay $300 for 15 total months in order to get his credit card balance down to $0.

In order to find this total, we need to take the amount he is going to pay per month ($300) and multiply is by the total number of months that he is going to be paying that amount (15):

$300 * 15 months = $4,500

The total amount of money that he is going to pay after his card balance reaches $0 is $4,500.

However, Colin only maxed out his credit card to $4,000 - the rest of the money is due to interest. So to find this amount, we take the total amount that he paid ($4,500) and subtract it from the total amount he initially maxed out his card with ($4,000):

$4,500 - $4,000 = $500

The amount of interest that Colin has paid when his credit card balance is $0 is $500.