List.Accumulate & Table.AddColum with Iteration Step Counter

Goodkat 

Instead of just iterating over the formula names, iterate over a list of records that include both the formula and its index:

let formulas = {"Deviation1", "Deviation2"}, components = { {"C1", "C2"}, {"C3", "C4"} }, baseTable = YourBaseTable, result = List.Accumulate( List.Zip({formulas, components}), baseTable, (state, current) => let formulaName = current{0}, compPair = current{1}, newCol = Table.AddColumn(state, formulaName, each [Record.Field(_, compPair{0})] - [Record.Field(_, compPair{1})]) in newCol ) in result

 Explanation

• formulas is your list of formula names.
• components is a list of field pairs used in each formula.
• List.Zip combines them into a list of {formulaName, {component1, component2}}.
• List.Accumulate loops through and adds a new column each time.
• The counter is implicitly handled by the position in the zipped list.