问题描述:

计算下面各题,怎样简便怎样算.
0.85×201
0.5×4.85×8
2.5×48-482.7+4.29+2.71+6.31.2×3.5+8.8×3.5.

网友答案:
解:(1)0.85×201,
=0.85×200+0.85×1,
=170+0.85,
=170.85;

(2)0.5×4.85×8,
=0.5×8×4.85,
=4×4.85,
=19.4;

(3)2.5×48-48,
=(2.5×4)×12-48,
=10×12-48,
=120-48,
=72;

(4)2.7+4.29+2.71+6.3,
=(2.7+6.3)+(4.29+2.71).
=9+7,
=16;

(5)1.2×3.5+8.8×3.5,
=(1.2+8.8)×3.5,
=10×3.5,
=35.
解析分析:(1)0.85×201,运用乘法分配律进行简算;(2)0.5×4.85×8,运用乘法交换律进行简算;(3)2.5×48-48,将原式转化为:2.5×4×12-48,然后运用乘法结合律进行简算;(4)2.7+4.29+2.71+6.3,运用加法交换律和结合律进行简算;(5)1.2×3.5+8.8×3.5,运用乘法分配律进行简算.

点评:此题考查的目的是理解掌握乘法、加法的运算定律,并且能够运用这些运算定律对小数四则混合运算进行简便计算.
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