在Excel中可以通过FACT函数来计算非负整数n的阶乘（n!)，而如果要通过VBA来计算阶乘，可以用下面的两个自定义函数：（参考美女MVP教你学Excel
VBA教程）
1.使用循环：
Function Factorial_a(ByVal Num As Integer)
If Num < 0 Then
Factorial_a = '#NUM!'
Else
Factorial_a = 1
For i = 1 To Num
Factorial_a = Factorial_a * i
Next
End If
End Function
2.使用递归：
Function Factorial_b(ByVal Num As Integer)
If Num < 0 Then
Factorial_b = '#NUM!'
ElseIf Num = 0 Or Num = 1 Then
Fac
1.使用循环：
Function Factorial_a(ByVal Num As Integer)
If Num < 0 Then
Factorial_a = '#NUM!'
Else
Factorial_a = 1
For i = 1 To Num
Factorial_a = Factorial_a * i
Next
End If
End Function
2.使用递归：
Function Factorial_b(ByVal Num As Integer)
If Num < 0 Then
Factorial_b = '#NUM!'
ElseIf Num = 0 Or Num = 1 Then
Fac