Need a bit of help.

A user enters some information into a textbox, in a format eg. 10*21. I want it so that when a user clicks Command1 or whatever, it works out the maths and places it in another textbox.
Eg.

Private Sub Command1_Click
Dim math As String
math = Form1.Text1.Text
'what go-
'es here?
End Sub

Any ideas?

Regards,
Phil