Sum skipping columns

[Steve]

In cell DC9 I want to enter a formula that will give me the sum of
E9+H9+K9+N9+...(every third column in row 9). Is this possible without
having to type out =E9+H9+...?

 

[Duke Carey]

=SUMPRODUCT(C9:N9,--(MOD(COLUMN(C9:N9)-2,3)=0))

 

[Duke Carey]

Oops-

=SUMPRODUCT(E9:Z9,--(MOD(COLUMN(E9:Z9)-2,3)=0))

 

[Don Guillett]

try this for row 4. correct for word wrap
=SUMPRODUCT((MOD(COLUMN(E4:INDEX(4:4,100))-CELL("Col",E4)+0,3)=0)*(E4:INDEX(
4:4,100)))

 

[Steve]

Worked perfectly. Thanks...huge timesaver.

Oops-

=SUMPRODUCT(E9:Z9,--(MOD(COLUMN(E9:Z9)-2,3)=0))

 

[Don Guillett]

Nice