Hiding multiple columns in Excel based on the value of a cell - vba

Question

I am trying to get columns to hide in a worksheet based on the value in a certain cell. This value could range from 1 to 30, and different columns are hidden for each possible option. I have the following code, but it doesn't seem to work all the time, and then sometimes it only hides some of the columns in the range, but not all (like if 5 was in cell AA1, then sometimes AN:AR will hide and AS:FC will not be hidden). If anyone has any ideas, I would appreciate the help. Thanks!
I have a sample workbook at: https://drive.google.com/file/d/0B8qPItN2DU0BZ3B0LW1XUS1BMFk/view?usp=sharing
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Range("AA1").Value = 1 Then
Columns("O:FC").EntireColumn.Hidden = True
Else
Columns("O:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 2 Then
Columns("T:FC").EntireColumn.Hidden = True
Else
Columns("T:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 3 Then
Columns("Y:FC").EntireColumn.Hidden = True
Else
Columns("Y:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 4 Then
Columns("AD:FC").EntireColumn.Hidden = True
Else
Columns("AD:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 5 Then
Columns("AI:FC").EntireColumn.Hidden = True
Else
Columns("AI:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 6 Then
Columns("AN:FC").EntireColumn.Hidden = True
Else
Columns("AN:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 7 Then
Columns("AS:FC").EntireColumn.Hidden = True
Else
Columns("AS:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 8 Then
Columns("AX:FC").EntireColumn.Hidden = True
Else
Columns("AX:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 9 Then
Columns("BC:FC").EntireColumn.Hidden = True
Else
Columns("BC:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 10 Then
Columns("BH:FC").EntireColumn.Hidden = True
Else
Columns("BH:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 11 Then
Columns("BM:FC").EntireColumn.Hidden = True
Else
Columns("BM:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 12 Then
Columns("BR:FC").EntireColumn.Hidden = True
Else
Columns("BR:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 13 Then
Columns("BW:FC").EntireColumn.Hidden = True
Else
Columns("BW:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 14 Then
Columns("CB:FC").EntireColumn.Hidden = True
Else
Columns("CB:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 15 Then
Columns("CG:FC").EntireColumn.Hidden = True
Else
Columns("CG:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 16 Then
Columns("CL:FC").EntireColumn.Hidden = True
Else
Columns("CL:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 17 Then
Columns("CQ:FC").EntireColumn.Hidden = True
Else
Columns("CQ:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 18 Then
Columns("CV:FC").EntireColumn.Hidden = True
Else
Columns("CV:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 19 Then
Columns("DA:FC").EntireColumn.Hidden = True
Else
Columns("DA:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 20 Then
Columns("DF:FC").EntireColumn.Hidden = True
Else
Columns("DF:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 21 Then
Columns("DK:FC").EntireColumn.Hidden = True
Else
Columns("DK:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 22 Then
Columns("DP:FC").EntireColumn.Hidden = True
Else
Columns("DP:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 23 Then
Columns("DU:FC").EntireColumn.Hidden = True
Else
Columns("DU:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 24 Then
Columns("DZ:FC").EntireColumn.Hidden = True
Else
Columns("DZ:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 25 Then
Columns("EE:FC").EntireColumn.Hidden = True
Else
Columns("EE:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 26 Then
Columns("EJ:FC").EntireColumn.Hidden = True
Else
Columns("EJ:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 27 Then
Columns("EO:FC").EntireColumn.Hidden = True
Else
Columns("EO:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 28 Then
Columns("ET:FC").EntireColumn.Hidden = True
Else
Columns("ET:FC").EntireColumn.Hidden = False
End If
If Range("AA1").Value = 29 Then
Columns("EY:FC").EntireColumn.Hidden = True
Else
Columns("EY:FC").EntireColumn.Hidden = False
End If
End Sub

Answer 1

Seems like there's a pattern of 5 columns per integer increase in the value in AA1, so:
Dim v, sht
Set sht = ActiveSheet
v = sht.Range("AA1").Value
sht.Columns("O:FC").EntireColumn.Hidden = False
If v >= 1 And v <= 30 Then
sht.Range(sht.Cells(1, 10+(5*v)), _
sht.Range("FC1")).EntireColumn.Hidden = True
End If
Although it's not particularly clear from the question exactly what the logic for hiding/showing is.

Answer 2

You are hiding a range of columns, and as your code is executed you are hiding, then re-displaying a lot of the columns.
You would be better to firstly display all columns in the largest range (O:FC) in your example, and then only hide the ones that match your value. So you could change the if else constructs to be a select case like this:
Columns("O:FC").EntireColumn.Hidden = False
select case Range("AA1").Value
case 1:
Columns("O:FC").EntireColumn.Hidden = True
case 2:
Columns("T:FC").EntireColumn.Hidden = True
' Add extra cases for each possible value
end select