Find SUM of diagonal entries in a range of values

Try array-entering this.

=SUM(IF(ROW(1:4)=COLUMN(A:D),A1:D4))

If you aren’t familiar with array-entered formulas array enter means the formula must be committed from edit mode by simultaneously pressing and holding down Ctrl and Shift while hitting Enter.

	A	B	C	D	E	F	G
1	1	2	3	4		4	In F1 array-entered
2	2	1	3	4			=SUM(IF(ROW(1:4)=COLUMN(A:D),A1:D4))
3	3	2	1	4
4	4	2	3	1

Mathfun,

You are welcome. Thank you for the feedback and the rep.

I failed to notice this thread was your first post. My apologies and welcome to the forum.

Here's another one that's a bit more robust.

Data Range

	C	D	E	F
5	26	0	89	68
6	95	97	91	85
7	5	92	99	24
8	16	87	35	87
9	------	------	------	------
10
11	309

This array formula**:

=SUM(IF(ROW(C5:F8)-ROW(C5)=COLUMN(C5:F8)-COLUMN(C5),C5:F8))

** array formulas need to be entered using the key
combination of CTRL,SHIFT,ENTER (not just ENTER).
Hold down both the CTRL key and the SHIFT key
then hit ENTER.

How about modify Tony's formula

=SUM(IF((ROW(F8)-ROW(C5:F8))=COLUMN(C5:F8)-COLUMN(C5),C5:F8))

You are welcome. Thank you for letting us know.