Converting between numbers and date

Say i have the following setup

http://img535.imageshack.us/img535/3655/67557494.png

What i am trying to do is, when the user clicks on the 'calculate age ' button it must calculate the age and display the result based upon the selection in the combobox i.e if 'Days' are selected then it must display in days, if weeks are selected then it must display in weeks..etc

Similarly when the user clicks on the 'convert to date' button , it must subtract the given days(or weeks or months or years) from Todays date and set it to the maskedbox

I also actually need to use the same maskedbox(by changing its mask) for Date Mode or Numeric mode, didn't mention it previously so as not to make it complex

vb Code:

Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        MaskedTextBox1.Text = "01-21-1990" 'example
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim dtDOB As Date
        Dim myTimeSpan As TimeSpan
 
        Date.TryParse(MaskedTextBox1.Text, dtDOB)
        myTimeSpan = Now.Subtract(dtDOB)
 
        '~~~ Here based on the seletion of item from the Combobox, display whatever you want
        Debug.Print("Days = " & myTimeSpan.TotalDays)
        Debug.Print("Years = " & myTimeSpan.TotalDays / 365)
        Debug.Print("Weeks = " & myTimeSpan.TotalDays / 52)
        Debug.Print("Months = " & myTimeSpan.TotalDays / 12)
    End Sub
End Class

...:wave: