用简便方法计算. (1)3.14×35+3.14×25(2)145×25%+14×2.2(3)87.5×19-87.5×8-87.5(4)0.77×(67+211)
方法
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用简便方法计算.
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(1)3.14×35+3.14×25,
=3.14×(35+25),
=3.14×1,
=3.14;(2)145×25%+14×2.2,
=1.8×14+14×2.2,
=14×(1.8+2.2),
=14×4,
=1;(3)87.5×19-87.5×8-87.5,
=87.5×19-87.5×8-87.5×1,
=87.5×(19-8-1),
=87.5×10,
=875;(4)0.77×(67+211),
=0.77×67+0.77×211,
=0.66+0.14,
=0.8.
