Sum of alternate columns & rows

I want to sum the alternate column/ row like (a1, c1, e1).

How can I do it.

Thanks

shubhkaran

You can use an array formula like this for columns A C E etc:

=SUM(IF(MOD(COLUMN(A1:E1),2)<>0,A1:E1))

Note, this is an array formula. You must press CTRL+SHIFt+ENTER for it to work