(1)25×125×4×8 =(25×4)×(125×8) =100×1000 =100000 (2)2005×2004÷4 =2005×(2004÷4) =2005×501 =2005×500+2005 =1002500+2005 =1004505 (3)55×66÷(11×11) =55×66÷11÷11 =(55÷11)×(66÷11) =5×6 =30