math, simple logic

[rpool]

is my logic problem?

I want that number "75", foreach 20
show result:
0
20
40
60
75

any advice please!

Private Sub Command1_Click()
Dim a As Integer
Dim b As Integer
Dim c As Integer

a = "75"

b = a Mod 20
c = a \ 20


Dim i As Integer
For i = 0 To a Step 20
List1.AddItem i
Next i

List1.AddItem b
List1.AddItem c


End Sub