I am trying to understand the algorithm used by My Calculators.com - Balloon Payment Calculator
If I enter the following details:
Loan amount: 4556.75 Number of months: 5 Interest rate: 5.75% Balloon payment: 3990.37
And click the 'View Amortization Schedule' button it displays me a breakdown of the payments and the totals. The value I am interested in is the total interest which in this example is
What is the formula used to end up with this figure? I have tried using IPMT in Excel but the figures returned do not match.