Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
        Dim total As Decimal
        Dim average As Decimal
        total = Val(txtDecember.Text) + Val(txtNovember.Text) + Val(txtOctober.Text) + Val(txtSeptember.Text) + Val(txtAugust.Text) + Val(txtJanuary.Text) + Val(txtFebruary.Text) + Val(txtMarch.Text) + Val(txtApril.Text) + Val(txtMay.Text) + Val(txtJune.Text) + Val(txtJuly.Text)
        lblTotal.Text = FormatNumber(total)
        average = total / 12
        lblAverage.Text = FormatNumber(average)
    End Sub
    Private Sub txtApril_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtApril.Validating
        'Validating input for April
        If Not IsNumeric(txtApril.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtApril.SelectionStart = 0
            txtApril.SelectionLength = txtApril.Text.Length
            e.Cancel = True
        ElseIf Val(txtApril.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtApril.SelectionStart = 0
            txtApril.SelectionLength = txtApril.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtAugust_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtAugust.Validating
        'Validating input for August
        If Not IsNumeric(txtAugust.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtAugust.SelectionStart = 0
            txtAugust.SelectionLength = txtAugust.Text.Length
            e.Cancel = True
        ElseIf Val(txtAugust.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtAugust.SelectionStart = 0
            txtAugust.SelectionLength = txtAugust.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtDecember_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtDecember.Validating
        'Validating input for December
        If Not IsNumeric(txtDecember.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtDecember.SelectionStart = 0
            txtDecember.SelectionLength = txtDecember.Text.Length
            e.Cancel = True
        ElseIf Val(txtDecember.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtDecember.SelectionStart = 0
            txtDecember.SelectionLength = txtDecember.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtFebruary_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtFebruary.Validating
        'Validating input for February
        If Not IsNumeric(txtFebruary.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtFebruary.SelectionStart = 0
            txtFebruary.SelectionLength = txtFebruary.Text.Length
            e.Cancel = True
        ElseIf Val(txtFebruary.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtFebruary.SelectionStart = 0
            txtFebruary.SelectionLength = txtFebruary.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtJanuary_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtJanuary.Validating
        'Validating input for January
        If Not IsNumeric(txtJanuary.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtJanuary.SelectionStart = 0
            txtJanuary.SelectionLength = txtJanuary.Text.Length
            e.Cancel = True
        ElseIf Val(txtJanuary.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtJanuary.SelectionStart = 0
            txtJanuary.SelectionLength = txtJanuary.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtJuly_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtJuly.Validating
        'Validating input for July
        If Not IsNumeric(txtJuly.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtJuly.SelectionStart = 0
            txtJuly.SelectionLength = txtJuly.Text.Length
            e.Cancel = True
        ElseIf Val(txtJuly.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtJuly.SelectionStart = 0
            txtJuly.SelectionLength = txtJuly.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtJune_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtJune.Validating
        'Validating input for June
        If Not IsNumeric(txtJune.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtJune.SelectionStart = 0
            txtJune.SelectionLength = txtJune.Text.Length
            e.Cancel = True
        ElseIf Val(txtJune.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtJune.SelectionStart = 0
            txtJune.SelectionLength = txtJune.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtMarch_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtMarch.Validating
        'Validating input for March
        If Not IsNumeric(txtMarch.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtMarch.SelectionStart = 0
            txtMarch.SelectionLength = txtMarch.Text.Length
            e.Cancel = True
        ElseIf Val(txtMarch.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtMarch.SelectionStart = 0
            txtMarch.SelectionLength = txtMarch.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtMay_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtMay.Validating
        'Validating input for May
        If Not IsNumeric(txtMay.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtMay.SelectionStart = 0
            txtMay.SelectionLength = txtMay.Text.Length
            e.Cancel = True
        ElseIf Val(txtMay.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtMay.SelectionStart = 0
            txtMay.SelectionLength = txtMay.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtNovember_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtNovember.Validating
        'Validating input for November
        If Not IsNumeric(txtNovember.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtNovember.SelectionStart = 0
            txtNovember.SelectionLength = txtNovember.Text.Length
            e.Cancel = True
        ElseIf Val(txtNovember.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtNovember.SelectionStart = 0
            txtNovember.SelectionLength = txtNovember.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtOctober_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtOctober.Validating
        'Validating input for October
        If Not IsNumeric(txtOctober.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtOctober.SelectionStart = 0
            txtOctober.SelectionLength = txtOctober.Text.Length
            e.Cancel = True
        ElseIf Val(txtOctober.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtOctober.SelectionStart = 0
            txtOctober.SelectionLength = txtOctober.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

    Private Sub txtSeptember_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtSeptember.Validating
        'Validating input for September
        If Not IsNumeric(txtSeptember.Text) Then
            MessageBox.Show("Must enter a number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtSeptember.SelectionStart = 0
            txtSeptember.SelectionLength = txtSeptember.Text.Length
            e.Cancel = True
        ElseIf Val(txtSeptember.Text) < 0 Then
            MessageBox.Show("Enter a postive number!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtSeptember.SelectionStart = 0
            txtSeptember.SelectionLength = txtSeptember.Text.Length
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
    'Clear all the text fields
    txtJanuary.Clear()
    txtFebruary.Clear()
    txtMarch.Clear()
    txtApril.Clear()
    txtMay.Clear()
    txtJune.Clear()
    txtJuly.Clear()
    txtAugust.Clear()
    txtSeptember.Clear()
    txtOctober.Clear()
    txtNovember.Clear()
    txtDecember.Clear()
    'Clear total and average rainfall labels
    lblTotal.Text = ""
    lblAverage.Text = ""
    'Reset the focus to january
    txtJanuary.Focus()
End Sub

Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
    'End the application
    End
    End Sub
End Class