求助vb编写程序怎么编？？？

Option Explicit

Function jc(lngNum As Long) As Long
Dim i As Long
jc = 1
For i = lngNum To 1 Step -1
jc = jc * i
Next
End Function
Private Sub Command1_Click()
s = jc(a) + jc(b) + jc(c)
End Sub

第二种
Option Explicit

Dim s As Long

Sub jc(lngNum As Long)
Dim i As Long
Dim temp As Long
temp = 1
For i = lngNum To 1 Step -1
temp = temp * i
Next
s = s + temp
End Sub
Private Sub Command1_Click()
s = 0
Call jc(a)
Call jc(b)
Call jc(c)
MsgBox s
End Sub