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Help with code for interest calculation formula visual basic 2008

Im having problems with getting the correct formula for this assignment. I did what the book says and its not working. I have to enter a principal and then in the multiline text box I have to have one column with the rate(%) which are 5,6,7,8,9 and 10 and then the other column has to be the amount after 10 years. It says the interest calculation formula is a=p(1+r)^n. This is what I got so far and nothing is appearing in my multiline text box.
Private Sub calculateButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles calculateButton.Click
' Declare Variables
Dim Principal As Decimal
Dim Rate As Double
Dim Amount As Decimal
Dim Output As String

' Retrieve User Input
Principal = Val(principalTextBox.Text)
Output = ResultTextBox.Text

' Set Output Header
Output = "Rate(%)" & ControlChars.Tab & ControlChars.Tab & "Amount after 10 years" & ControlChars.CrLf

' Calculate Amount
For years As Integer = 5 To 10
Amount = _
Principal * ((1 + Rate) ^ 10)
Output = ("5" & ControlChars.Tab & ControlChars.Tab & _
String.Format("{0:C}", Amount) & ControlChars.CrLf)
Next

End Sub

Any help please im getting frustrated.

wdosanjos

Try this:

Private Sub calculateButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles calculateButton.Click
        ' Declare Variables
        Dim Principal As Decimal
        Dim Rate As Double
        Dim Amount As Decimal
        Dim Output As String

        ' Retrieve User Input
        Principal = Val(principalTextBox.Text)
        Output = ResultTextBox.Text & ControlChars.CrLf

        ' Set Output Header
        Output = Output & "Rate(%)" & ControlChars.Tab & ControlChars.Tab & "Amount after 10 years" & ControlChars.CrLf

        ' Calculate Amount
        For years As Integer = 5 To 10
            Amount = _
            Principal * ((1 + Rate) ^ 10)
            Output = Output & ("5" & ControlChars.Tab & ControlChars.Tab & _
                       String.Format("{0:C}", Amount) & ControlChars.CrLf)
        Next
       
        ResultTextBox.Text = Output

    End Sub

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goldfingerpunk

ASKER

It calculated but now the problem is it has one column of all 5's and the other column is the same number too

ASKER CERTIFIED SOLUTION

wdosanjos

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