INDEX / MOD() question..

[Nastech]

hi, not sure if need use of MOD, or INDEX / OFFSET..
I have 10 double columns of numbers, only need the 1st col of every other
column (lo & hi figures),
to figure into a portion of a different formula.

will need to be able to externally (by a fixed/ absolute cell) select the
1st column, from every
other (2) column set of 20 columns. will only use one column for the -end
formula I need.

(specifically, FE - FX need to be able to select 1 column, out of every
other column starting at col FE, FG FI FK..),
have a fixed cell where designating number of columns to offset: $C$2
not sure how to apply, but think MOD is needed? thanks

have 2nd portion of formula figured out,
1st portion X: trying to grab data from 2 'LO' / hi columns (out of 20
lo-hi columns):

End Fromula:
=X (every other col by $C$2: FE FG FI FK..) /OFFSET(EF9,0,$C$2-1)%-100

would answer be something like: SUMPRODUCT(INDEX(MOD( ...
/OFFSET(EF9,0,$C$2-1)%-100


some examples of similar formula's:

=SUM(--(MOD(COLUMN($FE9:$FX9),2)>MOD(COLUMN($FE9),2)),$FE9:$FX9)

=SUMPRODUCT(--(MOD(COLUMN($FE9:$FX9),2)=MOD(COLUMN($FE9),2)),$FE9:$FX9,$FF9:$FW9)

INDEX: cumulative sum of x days percent change
=IF(J9=0,"",SUMPRODUCT(EF9:INDEX(EF9:EX9,1,$C$2)/EG9:INDEX(EG9:EY9,1,$C$2)%-100))

 

[Nastech]

Different way of putting it..

=INDEX(FE450:FX450,1,$C$2)

works for single rows, but double row sets of 2 columns - numbers lo & hi.
1 in $C$2 correctly gets 1st col. need 2 to select 3rd col (2nd 'lo' in
2nd set of 2 columns) etc thru 10 sets avail of 20 columns.