:let l=[] :for i in range(4) let l+=map(split(getline(i+1),'\_s'),'str2nr(v:val)') endfor :%d :for i in range(9) let l[i+3]-=l[i%3] endfor :call setline(1, (l[3]*l[7]*l[11]+l[6]*l[10]*l[5]+l[9]*l[4]*l[8]-l[5]*l[7]*l[9]-l[8]*l[10]*l[3]-l[11]*l[4]*l[6])/6) ZZ