Welcome to QB. Nice block setting. Depending on the size of your blocks
you can work it out on graph paper. It's like a log cabin. You start with
a square, add a rectangle on each side, then add (small square + rectangle
+ small square to top and bottom) and carry on.
On second thought and to make things easier I would probably draw the
block setting first then decide on block size otherwise you might end up with
some odd size. Hope this helps.