题目内容

能简便计算的尽量用简便方法计算
37×49+37×51108×2525×125×2×4
56×99+56124×75-124×72-124×2104×39-39×4.

解:(1)37×49+37×51,
=37×(49+51),
=37×100,
=3700;

(2)108×25,
=27×4×25,
=27×(4×25),
=27×100,
=2700;

(3)25×125×2×4,
=(25×4)×(125×2),
=100×250,
=25000;

(4)56×99+56,
=56×(99+1),
=56×100,
=5600;

(5)124×75-124×72-124×2,
=124×(75-72-2),
=124×1,
=124;

(6)104×39-39×4,
=(104-4)×39,
=100×39,
=3900.
分析:(1)(4)(5)(6)运用乘法分配律简算;
(2)把108分解成27×4,再运用乘法结合律简算;
(3)运用乘法交换律和结合律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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