Hello, working on this program for class. It states that it should ask 2 questions about each floor. (How many rooms are occupied on the floor? How many rooms are vacant on the floor?)

I have set the parameters for values at (7 floors, 30 rooms per floor.)

Now here is where I am getting thrown. How can I get the program to recognize the value entered for vacancies so that I will end up with an even 30 rooms per floor each time? Now I am able to enter up to 30 for each vacancy/occupancy and can end up with up to 60 rooms per floor.

Is there a way for the program to acknowledge the first value entered so that the precise value can be entered after?

Here is what I am working with so far. Thanks.

Code:
Public Class frmGalaxyHotel

    Private decTotalOccupied As Decimal
    Private decTotalVacant As Decimal
    Const decTotalRooms As Decimal = 210




    Private Sub frmGalaxyHotel_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        lstOccupied.Items.Clear()
        lstVacant.Items.Clear()
        lblTotalRooms.Visible = False
        lblTotalVacant.Visible = False
        lblTotalOccupied.Visible = False
        lblOccupanyRate.Visible = False
        btnOccupancy.Enabled = False

    End Sub

    Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnVacancy.Click
        'The button calculate click event accepts and displays up to 7 values each of occupied
        'and vacant rooms. Then calcuates and displays results

        Dim strRoomsVacant As String
        Dim decRoomsVacant As String
        Dim strInputMessage As String = "Enter the number of vacant rooms on floor # "
        Dim strInputHeading As String = "Galaxy Hotel"
        Dim strVacancyMessage As String = "Enter the number of vacant rooms on floor # "
        Dim strNonNumericError As String = "ERROR- Enter a numeric value only"
        Dim strNegativeError As String = "ERROR- Enter a positive numeric value. There are 30 rooms per floor. "

        'Loop Variables
        Dim strCancelClicked As String = ""
        Dim intNumberOfEntries As Integer = 1
        Dim intMaxNumberOfEntries As Integer = 7

        strRoomsVacant = InputBox(strInputMessage & intNumberOfEntries, strInputHeading, " ")

        Do Until intNumberOfEntries > intMaxNumberOfEntries Or strRoomsVacant = strCancelClicked
            If IsNumeric(strRoomsVacant) Then
                decRoomsVacant = Convert.ToDecimal(strRoomsVacant)
                If decRoomsVacant > 0 And decRoomsVacant <= 30 Then
                    lstVacant.Items.Add(decRoomsVacant)
                    decTotalVacant += decRoomsVacant
                    intNumberOfEntries += 1
                    strInputMessage = strVacancyMessage
                Else
                    strInputMessage = strNegativeError
                End If
            Else
                strInputMessage = strNonNumericError
            End If

            If intNumberOfEntries <= intMaxNumberOfEntries Then
                strRoomsVacant = InputBox(strInputMessage & intNumberOfEntries, strInputHeading, " ")
            End If
        Loop

        btnOccupancy.Enabled = True
        btnVacancy.Enabled = False

    End Sub

    Private Sub mnuClear_Click(sender As Object, e As EventArgs) Handles mnuClear.Click

        lstOccupied.Items.Clear()
        lstVacant.Items.Clear()
        lblRooms.Visible = False
        lblVacant.Visible = False
        lblOccupied.Visible = False
        lblRate.Visible = False
        lblTotalRooms.Visible = False
        lblTotalVacant.Visible = False
        lblTotalOccupied.Visible = False
        lblOccupanyRate.Visible = False
        btnOccupancy.Enabled = False

    End Sub

    Private Sub btnOccupancy_Click(sender As Object, e As EventArgs) Handles btnOccupancy.Click

        Dim strRoomsOccupied As String
        Dim decRoomsOccupied As Decimal
        Dim decOccupancyRate As Decimal = 0
        Dim strInputMessage As String = "Enter the number of occupied rooms on floor # "
        Dim strInputHeading As String = "Galaxy Hotel"
        Dim strOccupancyMessage As String = "Enter the number of occupied rooms on floor # "
        Dim strNonNumericError As String = "ERROR- Enter a numeric value for floor # "
        Dim strNegativeError As String = "ERROR- Enter a positive numeric value. There are 30 rooms per floor. "


        'Loop Variables
        Dim strCancelClicked As String = ""
        Dim intNumberOfEntries As Integer = 1
        Dim intMaxNumberOfEntries As Integer = 7

        strRoomsOccupied = InputBox(strInputMessage & intNumberOfEntries, strInputHeading, " ")

        Do Until intNumberOfEntries > intMaxNumberOfEntries Or strRoomsOccupied = strCancelClicked
            If IsNumeric(strRoomsOccupied) Then
                decRoomsOccupied = Convert.ToDecimal(strRoomsOccupied)
                If decRoomsOccupied > 0 And decRoomsOccupied <= 30 Then
                    lstOccupied.Items.Add(decRoomsOccupied)
                    decTotalOccupied += decRoomsOccupied
                    intNumberOfEntries += 1
                    strInputMessage = strOccupancyMessage
                Else
                    strInputMessage = strNegativeError
                End If
            Else
                strInputMessage = strNonNumericError
            End If

            If intNumberOfEntries <= intMaxNumberOfEntries Then
                strRoomsOccupied = InputBox(strInputMessage & intNumberOfEntries, strInputHeading, " ")
            End If
        Loop

        'Calculates and displays occupany rate
        If intNumberOfEntries > 1 Then
            lblOccupanyRate.Visible = True
            decOccupancyRate = decTotalVacant / decTotalOccupied
            lblOccupanyRate.Text = decOccupancyRate.ToString("P")
        Else
            MsgBox("Please Enter A Numeric Value")
        End If

        'Calculates and displays total vacant rooms
        lblTotalVacant.Visible = True
        lblTotalVacant.Text = decTotalVacant

        'Calculates and displays total occupied rooms
        lblTotalOccupied.Visible = True
        lblTotalOccupied.Text = decTotalOccupied

        'Displays total # of rooms in hotel
        lblTotalRooms.Visible = True
        lblTotalRooms.Text = decTotalRooms


    End Sub
End Class