题目内容

①2003+2002-2001-2000+1999+1998-1997-1996+…+7+6-5-4+3+2-1
②95×125+125×14-25×5
③99999×7+11111×37
④0.125×0.25×0.5×64
⑤13.5×9.9+6.5×10.1
⑥17.42-(3.36-2.58)-6.64
⑦48×29+13×16.
分析:①把原式转化为2003+2002-2001-(2000-1999)+(1998-1997)-…-(4-3)+(2-1),四个数一组相互抵消,2000是被4整除的,也就是说2000以后的数都可以相互抵消,最后剩下2003+2002-2001=2004;
②原式=95×125+125×14-125,然后根据乘法分配律进行简算;
③原式=11111×9×7+11111×37=11111×63+11111×37,然后运用乘法分配律进行简算;
④原式=0.125×0.25×0.5×64=0.125×0.25×0.5×8×8,然后运用乘法交换律和结合律,进行简算;
⑤原式=13.5×9.9+6.5×10.1=13.5×9.9+6.5×(9.9+0.2)=13.5×9.9+6.5×9.9+1.3,然后运用乘法分配律,提取9.9,然后解答即可;
⑥原式=17.42-(3.36-2.58)-6.64=17.42-3.36+2.58-6.64=(17.42+2.58)-(6.64+3.36),然后解答即可.
⑦把48拆分成16×3,即16×3×29+13×16=16×87+13×16,然后运用乘法分配律进行简算.
解答:解:①2003+2002-2001-2000+1999+1998-1997-1996+…+7+6-5-4+3+2-1
=2003+2002-2001-(2000-1999)+(1998-1997)-…-(4-3)+(2-1),
=2003+2002-2001-1+1-…-1+1,
=2003+2002-2001,
=2004;

②95×125+125×14-25×5,
=95×125+125×14-125,
=125×(95+14-1),
=125×108,
=125×8×16,
=1000×16,
=16000;

③99999×7+11111×37,
=11111×9×7+11111×37,
=11111×63+11111×37,
=11111×(63+37),
=1111100;

④0.125×0.25×0.5×64,
=0.125×0.25×0.5×64,
=0.125×0.25×0.5×8×8,
=(0.125×8)×(0.25×8)×0.5,
=1×2×0.5,
=1;

⑤13.5×9.9+6.5×10.1,
=13.5×9.9+6.5×10.1,
=13.5×9.9+6.5×(9.9+0.2),
=13.5×9.9+6.5×9.9+1.3,
=9.9×(13.5+6.5)+1.3,
=198+1.3,
=199.3;

⑥17.42-(3.36-2.58)-6.64,
=17.42-(3.36-2.58)-6.64,
=17.42-3.36+2.58-6.64,
=(17.42+2.58)-(6.64+3.36),
=20+10,
=30;

⑦48×29+13×16,
=16×3×29+13×16,
=16×87+13×16,
=16×(87+13),
=1600.
点评:此题应认真审题,根据数的特点,进行灵活解答,熟练运用运算定律是解答此题的关键.
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