Introduction

The compound interest is the amount of money earned on a deposit during a period of time. It can be calculated using the following formula:

Practical Learning: Starting the Exercise

1. Start Microsoft Access and create a blank database named Compound Interest
2. On the main menu, click Insert -> Forms
3. On the New Forms dialog box, make sure Design View is selected and make sure the combo box is empty:
    
   
4. Click OK
5. Display the Properties window. If you are using MS Access >= 2000, on the Properties window, set the Allow All Design Changes to Design View Only
6. Save the form as CompInterest
7. Change its properties as follows:
   Caption:                Compound Interest
   Record Selectors:    No
   Navigation Buttons: No
   Border Style:          Dialog
8. To add the first control, while the form is selected, on the Toolbox, make sure the Control Wizard button is down . Click the Group Box control and click somewhere in the form
9. In the first page of the wizard, click under Label Names
10. Type Monthly and press the down arrow key. Complete the label names with Quarterly, Semiannually, and Annually 
11. Click Next
12. Accept to have the default set to Monthly and click Next
13. Accept the default values and click Next
14. Accept the Option Buttons and click Next
15. Set the Caption to Compound Frequency and click Finish
16. Change the Name of the new group box control to fraFrequency
17. Design the dialog box and change the properties of the controls as follows:
     

    GroupBox: Caption: Preparation TextBox Label Caption TextBox Name Format Decimal Places Default Value Principal: txtPrincipal Currency 2 0 Interest Rate: txtInterestRate Percent   0.0825 Periods: txtPeriods General Number 0 0 GroupBox: Caption: Results TextBox Label Caption TextBox Name Format Decimal Places Default Value Interest Earned: txtInterestEarned Currency 2 0 Amount Earned: txtAmountEarned Currency 2 0

18. Implement the Click() event of the Calculate button as follows:
     

    Option Compare Database Option Explicit Private Sub cmdCalculate_Click() Dim Principal As Currency Dim InterestRate As Double Dim InterestEarned As Currency Dim FutureValue As Currency Dim RatePerPeriod As Double Dim Periods As Integer Dim CompoundType As Integer Dim i As Double Dim n As Integer Principal = CCur(txtPrincipal) InterestRate = CDbl(txtInterestRate) If fraFrequency.Value = 1 Then CompoundType = 12 ElseIf fraFrequency.Value = 2 Then CompoundType = 4 ElseIf fraFrequency.Value = 3 Then CompoundType = 2 Else CompoundType = 1 End If Periods = CInt(txtPeriods) i = InterestRate / CompoundType n = CompoundType * Periods RatePerPeriod = InterestRate / Periods FutureValue = Principal * ((1 + i) ^ n) InterestEarned = FutureValue - Principal txtInterestEarned = CStr(InterestEarned) txtAmountEarned = CStr(FutureValue) End Sub Private Sub cmdClose_Click() On Error GoTo Err_cmdClose_Click DoCmd.Close Exit_cmdClose_Click: Exit Sub Err_cmdClose_Click: MsgBox Err.Description Resume Exit_cmdClose_Click End Sub

19. Test the form