I want to clear the entire contents so that when a different selection is made on one of the checkboxes, only that data is displayed when the calculate button is depressed.

Here's my code:

Public Class LoanCalc

Private Sub butCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butCalc.Click
'This procedure executes when the user clicks the Calculate
'button to produce a loan payment based on the requirements
'as stated in the service request.

'Variable Declarations
Dim douPrincipal As Double = Me.txtPrincipal.Text
Dim douInterest() As Double = {5.35, 5.5, 5.75}
Dim decYears() As Decimal = {7, 15, 30}
Dim douPayment As Double
Dim douRemainingBalance As Double
Dim douInterestPaid As Double
Dim intNumberPayments As Integer
Dim intPaymentNumber As Integer

If Me.CheckBox1.Checked Then

'set the initial balance to the principal amount
douRemainingBalance = douPrincipal

'Calculate the payment
douPayment = ((douPrincipal * (douInterest(0) / 100) / 12) / (1 - Math.Pow(1 + (douInterest(0) / 100) / 12, -(decYears(0) * 12))))
intNumberPayments = decYears(0) * 12
'calculate payment, principal, accruedInterest, remainingbalance
For intPaymentNumber = 1 To intNumberPayments

'Calculates the interest paid with each payment and the remaining balance
douInterestPaid = douRemainingBalance * (douInterest(0) / 100 / 12) 'interest paid for current month is the (remaining balance)*(the monthly interest rate... i.e. the interest rate, as a dec., divided by 12)
douRemainingBalance = douRemainingBalance - (douPayment - douInterestPaid) ' subtract the princial payment portion of the monthly payment amount from the remaining balance

'Append data to the dataGridView
DataGridView1.Rows.Add(intPaymentNumber, FormatCurrency(douPayment, 2), FormatCurrency(douPrincipal, 2), FormatCurrency(douInterestPaid, 2), FormatCurrency(douRemainingBalance, 2))

Next

ElseIf Me.CheckBox2.Checked Then

'set the initial balance to the principal amount
douRemainingBalance = douPrincipal

'Calculate the payment
douPayment = ((douPrincipal * (douInterest(1) / 100) / 12) / (1 - Math.Pow(1 + (douInterest(1) / 100) / 12, -(decYears(1) * 12))))
intNumberPayments = decYears(1) * 12
'calculate payment, principal, accruedInterest, remainingbalance
For intPaymentNumber = 1 To intNumberPayments

'Calculates the interest paid with each payment and the remaining balance
douInterestPaid = douRemainingBalance * (douInterest(1) / 100 / 12) 'interest paid for current month is the (remaining balance)*(the monthly interest rate... i.e. the interest rate, as a dec., divided by 12)
douRemainingBalance = douRemainingBalance - (douPayment - douInterestPaid) ' subtract the princial payment portion of the monthly payment amount from the remaining balance

'Append data to the dataGridView
DataGridView1.Rows.Add(intPaymentNumber, FormatCurrency(douPayment, 2), FormatCurrency(douPrincipal, 2), FormatCurrency(douInterestPaid, 2), FormatCurrency(douRemainingBalance, 2))

Next
ElseIf Me.CheckBox3.Checked Then
'set the initial balance to the principal amount
douRemainingBalance = douPrincipal

'Calculate the payment
douPayment = ((douPrincipal * (douInterest(2) / 100) / 12) / (1 - Math.Pow(1 + (douInterest(2) / 100) / 12, -(decYears(2) * 12))))
intNumberPayments = decYears(2) * 12
'calculate payment, principal, accruedInterest, remainingbalance
For intPaymentNumber = 1 To intNumberPayments

'Calculates the interest paid with each payment and the remaining balance
douInterestPaid = douRemainingBalance * (douInterest(2) / 100 / 12) 'interest paid for current month is the (remaining balance)*(the monthly interest rate... i.e. the interest rate, as a dec., divided by 12)
douRemainingBalance = douRemainingBalance - (douPayment - douInterestPaid) ' subtract the princial payment portion of the monthly payment amount from the remaining balance

'Append data to the dataGridView
DataGridView1.Rows.Add(intPaymentNumber, FormatCurrency(douPayment, 2), FormatCurrency(douPrincipal, 2), FormatCurrency(douInterestPaid, 2), FormatCurrency(douRemainingBalance, 2))

Next
End If
End Sub

Private Sub butEXIT_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butEXIT.Click
'This procedure exits the program when the user clicks the EXIT button
Me.Close()
End Sub
End Class

Answered by __avd 1,826 in a post from

Source program must be surrounded with BB code tags: See # icon at toolbar and also read How to use bb code tags?.

Mark this thread as "Solved" if you get solution.