解题思路:(1)(2)(7)(8)(9)(10)(12)(13)(14)(15)(16)(17)运用乘法分配律简算;(3)(4)(5)运用乘法交换律简算;(6)先把32分解成8×4,再运用乘法结合律简算;(11)(18)按照先算乘除,再算加减,有括号的先算括号里面的顺序计算.
(1)([1/5]+[1/3])×15,
=[1/5]×15+[1/3]×15,
=3+5,
=8;
(2)[4/7]×[5/9]+[3/7]×[5/9],
=([4/7]+[3/7])×[5/9],
=1×[5/9],
=[5/9];
(3)[1/3]×[5/16]×[3/5],
=[1/3]×[3/5]×[5/16],
=[1/5]×[5/16],
=[1/16];
(4)2.5×97×0.4,
=(2.5×0.4)×97,
=1×97,
=97;
(5)1.25×97×8,
=(1.25×8)×97,
=10×97,
=970;
(6)1.25×32×2.5×97,
=1.25×8×4×2.5×97,
=(1.25×8)×(4×2.5)×97,
=10×10×97,
=9700;
(7)0.36×101,
=0.36×(100+1),
=0.36×100+0.36×1,
=36+0.36,
=36.36;
(8)0.36×98,
=0.36×(100-2),
=0.36×100-0.36×2,
=36-0.72,
=35.28;
(9)[5/7]-[5/9]×[5/7],
=(1-[5/9])×[5/7],
=[4/9]×
点评:
本题考点: 整数、分数、小数、百分数四则混合运算;运算定律与简便运算;分数的简便计算.
考点点评: 运算定律是常用的简便运算的方法,要熟练掌握,灵活运用.