Requirements:

Loan Amount Text Box

Fixed Interest Rate Text Box

Years Combo Box

To be calculated:

Monthly Payments

Number of Payments

Payment Total

Interest Total

Buttons:

Calculate and Exit

I have the correct calculations appearing in the Monthly Payments and Number of Payments. But when I try to use a pmt function for payment total and interest total, I can't get it to work. They way I have it constructed to calculate those two fields, the math is off from the calculators I am using to help work the math to check it. Online Calculator

Here is my code... Things I need assistance on: Payment Total And Interest Total. Either help with how to do the pmt function or help with fixing my code that I currently have.

Public Class Form1 Dim Nullable As TextBox Private Sub Form_load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Me.cboYears.SelectedText = "30" End Sub Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click Me.Close() End Sub Private Sub btnCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalc.Click 'Ensure that fields are entered to stave off errors running program. If String.IsNullOrEmpty(txtLoanAmount.Text) Then MessageBox.Show("Missing Amount", "Please Enter Amount of Loan") ElseIf String.IsNullOrEmpty(txtInterestRate.Text) Then MessageBox.Show("Missing Interest", "Please Enter Fixed Interest Rate") Else Dim LoanAmount As Double Dim InterestRate As Double Dim Years As Double Dim Months As Double LoanAmount = CDbl(txtLoanAmount.Text) InterestRate = txtInterestRate.Text / 12 Years = CDbl(cboYears.Text) Months = cboYears.Text * 12 'Monthly Payment Calculations and Number of Monthly Payments. txtMonthPayment.Text = Pmt(InterestRate, Months, -LoanAmount) txtMonthPayment.Text = Format(CDbl(txtMonthPayment.Text), "$###,###,###.##") txtNumPayment.Text = Months 'Payment Total Calculations. txtPaymentTotal.Text = txtMonthPayment.Text * txtNumPayment.Text txtPaymentTotal.Text = Format(CDbl(txtPaymentTotal.Text), "$###,###,###.##") 'Total of Interests Paid. txtInterestTotal.Text = txtPaymentTotal.Text - txtLoanAmount.Text txtInterestTotal.Text = Format(CDbl(txtInterestTotal.Text), "$###,###,###.##") End If End Sub End Class

One common problem I get when trying to do pmt function with the payment total is an error about infinite number. Which I thought was weird, so I figured I was blowing something up. I can't find a clear post about how pmt function works, or a post where someone did a similar mortgage calculator.

Thanks!