How do I figure the Sq Footage of a yard? Just lxw? what if it is uneven like 100 on one side and 65 on the other side and 50 by 70 on front and back? Is that how you determine sq ft of a yard. Also how do you figure the # of yards of mulch you need per area? Thanks and sorry if its should be common sense, I just want to make sure I'm doing it the right way.