370+261+149 =370+(261+149) =370+410 =780 (加法结合律) 234-(134+50) =234-134-50 =100-50 =50 (减法的运算性质) 2×17×50 =2×50×17 =100×17 1700 (乘法交换律) 37×4×25 =37×(4×25) =37×100 =3700 (乘法结合律) (30+25)×40 =30×40+25×40 =1200+1000 =2200 (乘法分配律) 8×4×25×125 =(4×25)×(8×125) =100×1000 =100000 (乘法交换律和乘法结合律)