Summing cell content in every 6th column

Hi all

I have a range of values which includes six columns headed:

buy date (BD), buy price (BP), sell date (SD), sell price(SP), profit (P), percentage (%)

This range of columns repeats to the right so that Buy Date starts in column B and repeats in Col H and Col M and Col S etc. as below:

Col A.........Col B......Col C.....Col D.....Col E.....Col F.....Col G.....Col H.....Col I.....etc

Formula.....BD..........BP.........SD.........SP..........P............%..........BD.........BP.......etc

Is there an elegant formula to:
a. Only sum the percentages in each row ie every sixth cell in a row starting from Col G,
b. Find the number of non empty percentage cells to be able to find the average % from a row and place the formula for the average in Col A for each row?

I have seen Dsum function however it works down columns not across rows. At least that's my understanding. I hope one of the wise ones can enlighten me.

I thank you in anticipation and look forward to a solution if one exists.

Regards

mgerada:

PS I have asked for summing every sixth column starting in column B maybe there is a formula for summing the nth column starting in column whatever?

this will sum cols g,m,s...
=SUMPRODUCT(--(MOD(COLUMN(B1:AA1),6)=1),B1:AA1)

Hi mgerada,

Find the attached with two possible ways.

I like Martin's formula but my method is easier. (maybe)