Factorial sub

[anish201]

I am trying to write a sub to get the factorial of a number. From the code below, can someone tell me why I need to have the fac = 1 line before the For Next loop?


Sub factorial()
Dim fac As Integer, i As Integer, Num As Integer
Num = Range("a1").Value
fac = 1
For i = 1 To Num
fac = i * fac
Next i
Range("a2").Value = fac
End Sub

[TonyJollans]

Because the uninitialised value of an integer is zero.

[Bob Phillips]

I am trying to write a sub to get the factorial of a number.

Why do you have the need for this sub, Excel has a Fact worksheet function


=FACT(5)

If you want to do many in a batch, it would still be more efficient to call the worksheet function from VBA



Sub factorial()
Range("a2").Value = Application.Fact(Range("a1").Value)
End Sub


simpler and more efficient

[Zack Barresse]

anish201 - here ya go

Also, guess I'll add my pence worth, as a Boolean UDF ...


Function ISFACTOR(lNum As Long, lFact As Long) As Boolean
ISFACTOR = Not CBool(lNum Mod lFact)
End Function