题目内容

【题目】计算下列各题,能简算的要用简便方法计算。

0.8×3.9×1.25    4.87×2.34+4.87×7.66     60.8-7.18-12.82

150.39-(15.39-8.74)      25.6×1.01 1.87+0.26+6.13+1.74

【答案】3.9;48.7;40.8

143.74;25.856;10

【解析】

(1)应用乘法交换律和乘法结合律进行简算;

(2)(5)应用乘法分配律进行简算;

(3)应用减法的性质进行简算;

(4)去掉括号,将原式变为150.39-15.39+8.74进行简算;

(6)应用加法交换律和加法结合律进行简算。

0.8×3.9×1.25

=(0.8×1.25)

=3.9×1

=3.9

4.87×2.34+4.87×7.66

=4.87×(2.34+7.66)

=4.87×10

=48.7

60.8-7.18-12.82

=60.8-(7.18+12.82)

=60.8-20

=40.8

150.39-(15.39-8.74)

=150.39-15.39+8.74

=135+8.74

=143.74

25.6×1.01

=25.6×(1+0.01)

=25.6×1+25.6×0.01

=25.6+0.256

=25.856

1.87+0.26+6.13+1.74

=(1.87+6.13)+(0.26+1.74)

=8+2

=10

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