Private Sub Command1_Click()
On Error GoTo errhandler
If Text1 <> "" Then
Print MsgBox((Text1 * (9 / 5)) + 32 & " degrees fahrenheit", , "The answer is...")
Else
Print MsgBox("Please enter a number", , "ERROR")
End If
Exit Sub
errhandler:
Print MsgBox("Please enter a number", , "ERROR")
End Sub

Private Sub Command2_Click()
On Error GoTo errhandler
If Text3 <> "" Then
Print MsgBox((Text3 - 32) * (5 / 9) & " degrees Celsius", , "The answer is...")
Else
Print MsgBox("Please enter a number", , "ERROR")
End If
Exit Sub
errhandler:
Print MsgBox("Please enter a number", , "ERROR")
End Sub

Private Sub Command3_Click()
Text1 = ""
Text3 = ""
End Sub

    Source: geocities.com/matkins70