Formula for decreasing value.

do you mean it starts at 8" LONG and the length decreases by 1/2 inch ?

Sorry for taking so long to get back

Could not figure out a single formula solution, but maybe this will work for you :omnifold.sol1.xlsx

Hope this helps

Sorry---was adding the saw curf, not subtracting..

Revised : omnifold.sol2.xlsx

Okay, Try this UDF solution, will work for both scenarios

Function CutBoard(StrtLeng, FrstCutLeng, CutIncr, Optional NumCutsPer, Optional IncldCurf, Optional CurfSz, Optional ReturnOpt)
    Dim LengthRemain, LastCut, NewCutLen
    Dim i, TotalCuts As Integer
    Dim ErrMess As String
    Dim EXIT_FLAG As Boolean
    If IsMissing(NumCutsPer) Then NumCutsPer = 1
    If IsMissing(IncldCurf) Then IncldCurf = 0
    If IsMissing(CurfSz) Then CurfSz = 1 / 8
    If IsMissing(ReturnOpt) Then ReturnOpt = 0
    ErrMess = ""
    If StrtLeng <= 0 Then
        ErrMess = "Invalid Starting Length"
    ElseIf FrstCutLeng <= 0 Or FrstCutLen > StrtLeng Then
        ErrMess = "Invalid First Cut Length"
    ElseIf CutIncr <= 0 Or CutIncr > FrstCutLeng Then
        ErrMess = "Invalid Cut Increment"
    ElseIf NumCutsPer < 1 Then
        ErrMess = "Cuts per cut length MUST be at Least 1"
    ElseIf IncldCurf <> 1 And IncldCurf <> 0 Then
        ErrMess = "Include Curf is not 1 or 0"
    ElseIf ReturnOpt < 0 Or ReturnOpt > 3 Then
        ErrMess = "Return Option MUST be 0,1,2 or 3"
    End If
    If ErrMess <> "" Then
        CutBoard = ErrMess
        Exit Function
    End If
    EXIT_FLAG = False
    TotalCuts = 0
    LengthRemain = StrtLeng
    NewCutLen = FrstCutLeng
    While LengthRemain > 0 And NewCutLen > 0 And EXIT_FLAG = False
    
        LastCut = NewCutLen
        If LengthRemain - (NewCutLen * NumCutsPer) > 0 Then
            LengthRemain = LengthRemain - (NewCutLen * NumCutsPer) - (IncldCurf * CurfSz * NumCutsPer)
            NewCutLen = NewCutLen - CutIncr
            TotalCuts = TotalCuts + NumCutsPer
        Else
            EXIT_FLAG = True
            For i = 1 To NumCutsPer
                If LengthRemain - NewCutLen > 0 Then
                    LengthRemain = LengthRemain - NewCutLen - (IncldCurf * CurfSz)
                    TotalCuts = TotalCuts + 1
                End If
            Next i
        End If
    Wend
    Select Case ReturnOpt
        Case 0
            CutBoard = TotalCuts
        Case 1
            CutBoard = LengthRemain
        Case 2
            CutBoard = LastCut
        Case 3
            CutBoard = "Total cuts : " & TotalCuts & " Last Cut Was : " & LastCut & " Length Remaining : " & LengthRemain
    End Select
End Function

to use, allow Macros,open VBA editor (Alt-F11), Insert Module, Copy & paste above into the module,save close editor

Parameters are
StrtLeng, FrstCutLeng, CutIncr, Optional NumCutsPer, Optional IncldCurf, Optional CurfSz, Optional ReturnOpt
StrtLeng - Starting length of your board, in decimal inches (ie 100 1/2 inches = 100.5)
FrstCutLeng - Length of your first cut(s) in decimal inches
CutIncr - length to decrease cut length by in decimal inches
NumCutsPer (Optional) - how many cuts to make at each Length (defaults to 1)
IncldCurf (Optional) - 1 = include saw curf,0 = don't include saw curf (defaults to 0)
CurfSz (Optional) - size of the saw blade curf in decimal inches (defaults to 0.125 (1/8"))
ReturnOptions (optional) 0- Total number of cuts made, 1- length of board left (if any) after as many cuts can be made using first 4 parameters, 2- the length of the last cut, in decimal inches, 3- a brief text summary of options 1,2&3 (defaults to 0)

See attachment for examples

Hope this helps

1) if you run out of decreases, doubling the starting board length wont increase the number of cuts, it will just increase the amount of board you have left at the end of the sequence of cuts
2) as for 2.5 cuts per lenth...how would you accomplish this? I have never been able to do it with my saw ! the number of cuts is supposed to be an integer, ( the display using the helper columns assumed an integer # of cuts, so you keep seeing 8"(I left it in for error checking the UDF)), however, this did point out a flaw in the logic of the UDF as well --- I did not check for that !!!

Function CutBoard(StrtLeng, FrstCutLeng, CutIncr, Optional NumCutsPer, Optional IncldCurf, Optional CurfSz, Optional ReturnOpt)
    Dim LengthRemain, LastCut, NewCutLen
    Dim i, TotalCuts, CutsPer As Long
    Dim ErrMess As String
    Dim EXIT_FLAG As Boolean
    If IsMissing(NumCutsPer) Then NumCutsPer = 1
    If IsMissing(IncldCurf) Then IncldCurf = 0
    If IsMissing(CurfSz) Then CurfSz = 1 / 8
    If IsMissing(ReturnOpt) Then ReturnOpt = 0
    If IsMissing(ForceCutsPerInt) Then ForceCutsPerInt = True
    CutsPer = NumCutsPer
    ErrMess = ""
    If StrtLeng <= 0 Then
        ErrMess = "Invalid Starting Length"
    ElseIf FrstCutLeng <= 0 Or FrstCutLen > StrtLeng Then
        ErrMess = "Invalid First Cut Length"
    ElseIf CutIncr <= 0 Or CutIncr > FrstCutLeng Then
        ErrMess = "Invalid Cut Increment"
    ElseIf CutsPer < 1 Or CutsPer - CLng(NumCutsPer) > 0 Then
        ErrMess = "Cuts per cut length MUST be at Least 1"
    ElseIf IncldCurf <> 1 And IncldCurf <> 0 Then
        ErrMess = "Include Curf is not 1 or 0"
    ElseIf ReturnOpt < 0 Or ReturnOpt > 3 Then
        ErrMess = "Return Option MUST be 0,1,2 or 3"
    End If
    If ErrMess <> "" Then
        CutBoard = ErrMess
        Exit Function
    End If
    EXIT_FLAG = False
    TotalCuts = 0
    LengthRemain = StrtLeng
    NewCutLen = FrstCutLeng
    While LengthRemain > 0 And NewCutLen > 0 And EXIT_FLAG = False
    
        LastCut = NewCutLen
        If LengthRemain - (NewCutLen * NumCutsPer) > 0 Then
            LengthRemain = LengthRemain - (NewCutLen * CutsPer) - (IncldCurf * CurfSz * CutsPer)
            NewCutLen = NewCutLen - CutIncr
            TotalCuts = TotalCuts + CutsPer
        Else
            EXIT_FLAG = True
            For i = 1 To CutsPer
                If LengthRemain - NewCutLen > 0 Then
                    LengthRemain = LengthRemain - NewCutLen - (IncldCurf * CurfSz)
                    TotalCuts = TotalCuts + 1
                End If
            Next i
        End If
    Wend
    Select Case ReturnOpt
        Case 0
            CutBoard = TotalCuts
        Case 1
            CutBoard = LengthRemain
        Case 2
            CutBoard = LastCut
        Case 3
            CutBoard = "Total cuts : " & TotalCuts & " Last Cut Was : " & LastCut & " Length Remaining : " & LengthRemain
    End Select
End Function

new code forces the number of cuts to an integr value, and I updated the Formula version as well to display interim results properly
Same Parameters as before

Hope this helps

Forgot the example , then I couldn't get back on!
Anyways, here''s the example

Remmeber, the UDF is displaying its results in Column I, the results returned in columns D,E and F are all from Excel Functions alone, just to visualize the What the UDF is doing