Examples: Compound Interest

	Compound Interest

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:

	P = Principal
	r = Annual (Interest) Rate
	m = Number of Compounding Periods per Year
	n = Total Number of Compounding Periods
	A = Amount Earned After n periods

Practical Learning: Starting the Exercise

Start Microsoft Access and create a blank database named Compound Interest
On the Ribbon, click Create
In the Forms section, click Form Design
Display the Properties window. On the Properties window, set the Allow All Design Changes to Design View Only
Save the form as CompInterest
Change its properties as follows:
Caption:                Compound Interest
Record Selectors:    No
Navigation Buttons: No
Border Style:          Dialog
To add the first control, while the form is selected, on the Ribbon, make sure the Use Control Wizard button is down. Click the Group Box control and click somewhere in the form
In the first page of the wizard, click under Label Names
Type Monthly and press the down arrow key. Complete the label names with Quarterly, Semiannually, and Annually
Click Next
Accept to have the default set to Monthly and click Next
Accept the default values and click Next
Accept the Option Buttons and click Next
Set the Caption to Compound Frequency and click Finish
Change the Name of the new group box control to fraFrequency

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

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

Test the form