Find Last Cell In Column And Paste Formula In Next Blank Cell Then Repeat On Remaining Columns

I need a macro to find the last cell in the column, then copy the formula to the next blank cell. Then, it goes back to the last cell (above) and paste's values. Then, go to the next column and repeat the process. I can do this but have to call each cell separatly...however, I would like to do it in a loop to simplify things. It would be great to even be able to just set the start and ending columns. Here is my current code:

Dim rng As Range, aCell As Range
Set rng = Range("C8, D8, E8, F8, G8, H8, J8, K8, L8, M8, N8, O8, P8, Q8, R8, S8, T8, U8")
For Each aCell In rng
Selection.End(xlDown).Select
Application.CutCopyMode = False

[Code] .......

It does not go to the next column, instead it stays in the same column and repeats the process.