Formula - Efficient way to assign signs (+/-) to numbers in alternating in a column

[Cubist]

I'm looking for an efficient way to turn column A into column B. I have a few ideas but what's the most efficient?

Book1
	A	B
1	From	To
2	+	5
3	5	2
4	+	-1
5	2	-8
6	-
7	1
8	-
9	8
Sheet13

 

[jolivanes]

What ideas did you have?
Maybe

Sub Concat_Offsets()
Dim lr As Long
lr = Cells(Rows.Count, 1).End(xlUp).Row
Application.ScreenUpdating = False
   With ActiveSheet
        If .AutoFilterMode Then .AutoFilterMode = False
            With .Range("A1:A" & lr)
                .AutoFilter 1, ">0"
                    With .Range("B2:B" & lr)
                        .Formula = "=R[-1]C[-1]&RC[-1]"
                    End With
            End With
        .AutoFilterMode = False
    End With
    With Range("B2:B" & lr)
        .Value = .Value
        .SpecialCells(xlCellTypeBlanks).Delete Shift:=xlUp
    End With
Application.ScreenUpdating = True
End Sub

 

[Joe4]

I don't know if it is the most efficient, but here is one way using strictly formulas (no VBA).
Formula to put in cell B2 and copy down to cell B5:

=VALUE(OFFSET($A$2,(ROW()*2)-4,0) & OFFSET($A$2,(ROW()*2)-3,0))

Results:

 

[Cubist]

Thanks for the above suggestions above. I'm looking for a formula instead of VBA.
@Joe4 I have a large range so I'm trying to avoid OFFSET if possible. I've been playing with this for a bit, this is the best I've come up with. I have a feeling there's a more concise way.

Book1
	A	B
1	From	To
2	+	5
3	5	2
4	+	-1
5	2	-8
6	-
7	1
8	-
9	8
Sheet4

Cell Formulas
Range	Formula
B2:B5	B2	=LET(w,WRAPROWS(A2:A9,2),IF(CHOOSECOLS(w,1)="+",1,-1)*CHOOSECOLS(w,2))
Dynamic array formulas.

 

[Tetra201]

Here is my take on this:

=INDEX(--(A2:A8&A3:A9),SEQUENCE((ROWS(A2:A8)+1)/2,,,2))

 

[Cubist]

@Tetra201 thanks for the idea of offsetting the range. This is what I came up with from that.

Book1
	A	B
1	From	To
2	+	5
3	5	2
4	+	-1
5	2	-8
6	-
7	1
8	-
9	8
Sheet4

Cell Formulas
Range	Formula
B2:B5	B2	=TOCOL(IF(A2:A8="+",1,-1)*A3:A9,2)
Dynamic array formulas.

 

[Tetra201]

Why not just

=TOCOL(--(A2:A8&A3:A9),2)

 

[Cubist]

Brilliant.

 

[Joe4]

Why not just

=TOCOL(--(A2:A8&A3:A9),2)

That is pretty cool! Why didn't you suggest it the first time around!

I must admit, there are a number of new functions I have not used much of yet, and TOCOL is one of those!

 

[Tetra201]

... Why didn't you suggest it the first time around!...

At that moment, I had access only to Excel 2021, which is lacking many new functions