[RC-Monster Mike]

I am no artist, but I will try to explain it a little better. Lets build one pack together:
In order to get 7.4 volts, we need 2, 3.7 volt cells (already established)

Let these represent the cells: II

Now, to have this 4000mah, 7.4volt pack become a 12000mah, 7.4 volt pack, we need to run two more sets of the same thing
(II + II)

So, altogether we need three sets of 2 cells per pack ( II+II+II) wired in parallel. So the total cell count per pack is 6.