题目内容
脱式计算. ①8.82×15-100 | ②15.8-+14.2-, | ③21.6-0.8×4÷0.8×4 |
④3×3.7+3.6+5.3×3 | ⑤5+0.45÷0.9-1.75 | ⑥1110÷[56×(-)] |
解:①8.82×15-100,
=132.3-100,
=32.3;
②15.8-+14.2-,
=(15.8+14.2)-(+),
=30-1,
=29;
③21.6-0.8×4÷0.8×4,
=21.6-3.2÷0.8×4,
=21.6-16,
=5.6;
④3×3.7+3.6+5.3×3,
=(3.7+5.3)×3+3.6,
=9×3+3.6,
=27+3.6,
=30.6;
⑤5+0.45÷0.9-1.75,
=5+0.5-1.75,
=5.5-1.75,
=3.75;
⑥1110÷[56×(-)],
=1110÷[56×-56×],
=1110÷[24-21],
=1110÷3,
=370.
分析:①按运算顺序计算,先算乘法,再算减法;
②运用加法交换律与结合律以及减法的性质简算;
③按运算顺序计算,先算0.8×4÷0.8×4,按运算顺序从左向右依次计算,最后算减法;
④运用乘法分配律简算;
⑤按运算顺序计算,先算除法,再按顺序从左向右依次计算;
⑥中括号内运用乘法分配律简算.
点评: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简便计算.
=132.3-100,
=32.3;
②15.8-+14.2-,
=(15.8+14.2)-(+),
=30-1,
=29;
③21.6-0.8×4÷0.8×4,
=21.6-3.2÷0.8×4,
=21.6-16,
=5.6;
④3×3.7+3.6+5.3×3,
=(3.7+5.3)×3+3.6,
=9×3+3.6,
=27+3.6,
=30.6;
⑤5+0.45÷0.9-1.75,
=5+0.5-1.75,
=5.5-1.75,
=3.75;
⑥1110÷[56×(-)],
=1110÷[56×-56×],
=1110÷[24-21],
=1110÷3,
=370.
分析:①按运算顺序计算,先算乘法,再算减法;
②运用加法交换律与结合律以及减法的性质简算;
③按运算顺序计算,先算0.8×4÷0.8×4,按运算顺序从左向右依次计算,最后算减法;
④运用乘法分配律简算;
⑤按运算顺序计算,先算除法,再按顺序从左向右依次计算;
⑥中括号内运用乘法分配律简算.
点评: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简便计算.
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