题目内容
计算下面各题.
75.7+39.4-23.86 | 21.21+38.38-9.79 |
47.28+1.39+52.72 | 2.45-1.68+1.54. |
分析:(1)(2)(4)按照从左到右的顺序计算;
(3)运用加法交换律简算.
(3)运用加法交换律简算.
解答:解:(1)75.7+39.4-23.86,
=115.1-23.86,
=91.24;
(2)21.21+38.38-9.79,
=59.59-9.79,
=49.8;
(3)47.28+1.39+52.72,
=47.28+52.72+1.39,
=100+1.39,
=101.39;
(4)2.45-1.68+1.54,
=0.77+1.54,
=2.31.
=115.1-23.86,
=91.24;
(2)21.21+38.38-9.79,
=59.59-9.79,
=49.8;
(3)47.28+1.39+52.72,
=47.28+52.72+1.39,
=100+1.39,
=101.39;
(4)2.45-1.68+1.54,
=0.77+1.54,
=2.31.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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