The division order decimal interest is derived by dividing your net mineral acres by the gross acres in a unit times the royalty interest set out in your lease. Your mother’s division order interest was most likely in 40, 160 or 640 acre units. Most wells drilled in Ellis County today are being drilled on larger units (1280 acres or more). Therefore the interest you are seeing is most likely smaller than the ones set out on your mother’s devision orders.