subroutine to calculate the sum of numbers in a row

[mbababrik]

ok im new to this wesite and a new user of VBA
I have a column of numbers, that I don’t know the length in advance, but is located in column A. I want to write a subroutine that calculates the sum of the following
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o> </o>
Sum=1<SUP>st</SUP> number* last number+ 2<SUP>nd</SUP> number*next to last number + 3<SUP>rd</SUP> number* 3<SUP>rd</SUP> to last number etc. If the total number of numbers is odd, the middle number will have nothing to pair it with. In this case, square the middle number and add it to the sum. Note that the column contains only numbers and blank lines, and blank lines are found only after the column has ended.
i got the part on how to determine if the number is odd or even
Sub checkifevenorodd()
Dim userentry As Long
userentry = WorksheetFunction.CountA(Columns(1))
userentrydiv2 = CInt(userentry / 2)
userentrydiv2times2 = userentrydiv2 * 2
If userentrydiv2times2 = userentry Then
MsgBox ("even")
Else
MsgBox ("odd")
End If
End Sub
i appreciate any help
thank you

 

[HalfAce]

Just out of curiosity, how does the longer version that I posted fare against your data?
Don't get me wrong, assuming all else is equal, I'd go with what Mike posted, I'm just curious how it handles the even and odd number of values issue.

 

[mikerickson]

I tested and found that if there are an even number of rows, MidValRo retains it's intial value of 0 and the second loops exits on the first pass.
Changing the second loop to

For Ro = 1 To LstRo [COLOR="Red"]/ 2[/COLOR]
  [COLOR="Red"]'[/COLOR]If Ro >= MidValRo Then Exit For
  TotalCount = TotalCount + Cells(Ro, "A") * Cells(LstRo, "A")
  LstRo = LstRo - 1
Next Ro

corrected that.

 

[HalfAce]

Sure enough - I missed it.

Thanks Mike.