题目内容
怎样简便怎样算:
①893-126-374
②45.6+2.37+4.4
③102×45
④32×125×25
⑤43×99+43
⑥(40+8)×25.
解:①893-126-374,
=893-(126+374),
=893-500,
=393;
②45.6+2.37+4.4,
=(45.6+4.4)+2.37,
=50+2.37,
=52.37;
③102×45,
=(100+2)×45,
=100×45+2×45,
=4500+90,
=4590;
④32×125×25,
=(8×125)×(4×25),
=1000×100,
=100000;
⑤43×99+43,
=43×(99+1),
=43×100,
=4300;
⑥(40+8)×25.
=40×25+8×25,
=1000+200,
=1200.
分析:①893-126-374,根据减法的运算性质,a-b-c=a-(b+c),进行简算.
②45.6+2.37+4.4,应用加法的交换律和结合律进行简算.
③102×45,转化为(100+2)×45,应用乘法分配律进行简算.
④32×125×25,把32分解为8×4,再应用乘法交换律和乘法结合律进行简算.
⑤43×99+43,应用乘法分配律进行简算.
⑥(40+8)×25.应用乘法分配律进行简算.
点评:此题考查的目的是灵活运用运算定律和运算性质进行简便计算.提高计算能力,提高做题的正确率.
=893-(126+374),
=893-500,
=393;
②45.6+2.37+4.4,
=(45.6+4.4)+2.37,
=50+2.37,
=52.37;
③102×45,
=(100+2)×45,
=100×45+2×45,
=4500+90,
=4590;
④32×125×25,
=(8×125)×(4×25),
=1000×100,
=100000;
⑤43×99+43,
=43×(99+1),
=43×100,
=4300;
⑥(40+8)×25.
=40×25+8×25,
=1000+200,
=1200.
分析:①893-126-374,根据减法的运算性质,a-b-c=a-(b+c),进行简算.
②45.6+2.37+4.4,应用加法的交换律和结合律进行简算.
③102×45,转化为(100+2)×45,应用乘法分配律进行简算.
④32×125×25,把32分解为8×4,再应用乘法交换律和乘法结合律进行简算.
⑤43×99+43,应用乘法分配律进行简算.
⑥(40+8)×25.应用乘法分配律进行简算.
点评:此题考查的目的是灵活运用运算定律和运算性质进行简便计算.提高计算能力,提高做题的正确率.
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