dynamic calculation, row and column operations

Hi there,
Please help. Say I have a 9by10 excel sheet, something like this:

0,83430155 0,580553842 0,348584099 0,420539842 0,583892886 0,46086388 0,810126559 0,830109017 0,843489139
0,049380668 0,566570026 0,300095114 0,016045539 0,568907809 0,73156691 0,201381596 0,025214578 0,96600303
0,650378556 0,896557871 0,399269313 0,99097527 0,716639937 0,309991158 0,084696007 0,434419509 0,392676138
0,923133369 0,507890355 0,779445044 0,075274557 0,920150345 0,252689235 0,206218027 0,271049924 0,052910757
0,404394479 0,751618217 0,771374923 0,349304944 0,843896301 0,891552716 0,166329907 0,84464468 0,23543607
0,219808845 0,133496878 0,02874144 0,178003019 0,929661147 0,682071652 0,984850578 0,959935047 0,973773127
0,247205959 0,544407774 0,373298892 0,010865352 0,010043074 0,459332076 0,12697625 0,938000947 0,208823788
0,283506258 0,043122548 0,037509503 0,712992584 0,92864103 0,157464012 0,571699336 0,207903276 0,364425613
0,260035824 0,160353106 0,126029825 0,593165782 0,513064422 0,315484001 0,474075262 0,273442445 0,971758478
0,751313457 0,058197364 0,762151656 0,736473387 0,901213079 0,997865927 0,327578452 0,645238879 0,003238067

I want to take sum of each 1st, 4th and 7th column while I am dragging down and 2nd, 3th, 5th, 6th, 8th and 9th while I am dragging to the right. As following:

SUM(A1:A10) | Sum(B1:B10)| SUM(C1:C10)
SUM(D1:D10)| Sum(E1:E10) | Sum(F1:F10)
SUM(G1:G10)| Sum(H1:H10) | Sum(I1:I10)

How can I do this using function, such as INDEX, ROW() etc.?

Hi JohnTopley,

it works, thanks a lot