VB利用自定义过程的方法求3！+5！+9！=?

Option Explicit

Function jc(a As Integer)
Dim i As Integer, j
j = 1
For i = 1 To a
j = j * i
Next
jc = j
End Function

Private Sub Command1_Click()
MsgBox "3！+5！+9！=" & jc(3) + jc(5) + jc(9)
End Sub

Function x(N As Integer) As Long
x = 1
For i = 1 To N
x = x * i
Next
End Function

Private Sub cmdCal_Click()
MsgBox x(3) + x(5) + x(9)
End Sub

private sub sum(a as integer,b as integer,c as integer)
dim i as integer
dim sum1 as integer,sum as integer
sum1=1
for i=1 to a
sum1=sum1*i
next i
sum=sum+sum1
sum1=1
for i=1 to b
sum1=sum1*i
next i
sum=sum+sum1
sum1=1
for i=1 to c
sum1=sum1*i
next i
sum=sum+sum1
form1.print "这三个数的阶乘的和为：";sum
end sub

Option Explicit

Sub Form_load()