Sum products of named columns - excel

Question

How do I sum all products of the columns in table with another table?
To make it more clear, look at the image attached. I want the column Cost of table TableA to be equal to
=sum([A]*Lookup([[A];[#Headers]]; Parameters[What]; Parameters[Cost]); ....)
And so on for every column of TableA.
I am however pretty much reluctant of doing it manually and trying to come up with formula to make it automatically, so if I add another column I don't have to modify the formula in column Cost
EDIT
What I have come up so far is something like this:
=sum(
[A]*Lookup([[A];[#Headers]]; Parameters[What]; Parameters[Cost]);
[B]*Lookup([[B];[#Headers]]; Parameters[What]; Parameters[Cost]);
[C]*Lookup([[C];[#Headers]]; Parameters[What]; Parameters[Cost])
)
I want to have a formula that will cover new column if I add one. So, let's say I've added a column named NEW, so the formula should automatically pick it up and effectively work like this:
=sum(
[A]*Lookup([[A];[#Headers]]; Parameters[What]; Parameters[Cost]);
[B]*Lookup([[B];[#Headers]]; Parameters[What]; Parameters[Cost]);
[C]*Lookup([[C];[#Headers]]; Parameters[What]; Parameters[Cost]);
[NEW]*Lookup([[NEW];[#Headers]]; Parameters[What]; Parameters[Cost])
)
The Parameters table will of course include a row with value NEW

Answer 1

If you want it to be (50*4+5*100+1*150) for item 1 then you can apply this formulae in cell B3 assuming that the word "cost is in cell B2
INDEX($B$7:$B$9,MATCH($C$2,$A$7:$A$9,0))*$C3+INDEX($B$7:$B$9,MATCH($D$2,$A$7:$A$9,0))*$D3+INDEX($B$7:$B$9,MATCH($E$2,$A$7:$A$9,0))*$E3

Answer 2

If the parameters in tables TableA and Parameters are in the same order, then you can use the following in column Cost:
=SUMPRODUCT(TRANSPOSE(TableA[#[A]:[C]])*Parameters[Cost])
Entered as array formula (i.e. type the formula then instead of pressing Enter, press Ctrl+Shift+Enter)
EDIT:
If the columns in TableA are not ordered, but those in Parameters are, then you can use the following (I'm not 100% sure it always works, but I've been testing a bit and it seems to work fine):
=SUMPRODUCT(TableA[#[A]:[C]]*LOOKUP(TableA[[#Headers],[A]:[C]],Parameters[What],Parameters[Cost]))
Doesn't need to be entered as array formula.

Answer 3

This answer is amended to take account of your statement that the columns of TableA do not necessarily match entries in the rows of the Parameters table.
If you don't mind using macro code, you could define your own function to do the job:
Option Explicit
Public Function TotalCost(rItemCodes As Range, rCostTable As Range, rItemCounts As Range) As Double
'// this function returns the total cost of an item using
'// a lookup into a table of costs from a code, multiplying
'// the item count by the corresponding cost
Dim rItemCount As Range
Dim rCost As Range
Dim rCode As Range
Dim rMatchingCode As Range
'// Define the code list as the first column of the cost table
Dim rCodeList As Range
Set rCodeList = rCostTable.Columns(1)
TotalCost = 0
Dim ix As Integer
'// Loop through every item code
For ix = 1 To rItemCodes.Columns.Count
Set rItemCount = rItemCounts.Cells(1, ix)
Set rCode = rItemCodes.Cells(1, ix)
Set rMatchingCode = Nothing
On Error Resume Next
'// Find the item that matches in the cost list
Set rMatchingCode = rCodeList.Find(rCode.Value, LookAt:=xlWhole)
'// Check it was found, and calculate the additional cost
If Not rMatchingCode Is Nothing Then
Set rCost = rMatchingCode.Cells(1, 2)
TotalCost = TotalCost + rItemCount.Value * rCost.Value
End If
On Error GoTo 0
Next ix
End Function
If you named the table of costs in the parameters table, say, CostTable (range A8:B10 in your example), and the heading row of table A, say, CodeList (range C1:E1 in your example) then the formula in B2 would be =TotalCost(CodeList,CostTable,C2:E2).