题目内容
简便计算: 2.5×3.2×12.5 |
6.3÷1.4 | 2.5×2.4 |
15.32×4+4.68÷0.25 | 2.55×1.5+1.5+6.45×1.5 | 2.95×101-2.95 |
3.12+3.12×99 | 15÷(0.15×0.4) | 2.55×1.5+1.5+6.45×1.5 |
73.8-1.64-13.8-5.36 | 6.75-(0.9+3.75) | 27.38-5.34+2.62-4.66 |
35.72-4.9-(5.72+5.1) | 0.73-0.25-0.73+0.25 | 5.3+0.1+5.3-0.1 |
12.7-4.8-5.2. |
分析:(1)将算式中的3.2改写成0.4乘以8的形式进行计算比较简便;
(2)将算式中的1.4改写成0.7乘以2的形式,然后再用6.3分别除以0.7与2,结果不变;
(3)将算式中的2.4改写成4乘以0.6的形式进行计算比较简便;
(4)将0.25改写成分数
,除以
等于乘以它的倒数,然后再利用乘法分配律进行计算即可得到答案;
(5)将算式中的加数1.5改写成1.5×1,然后再利用乘法分配律进行计算即可得到答案;
(6)直接利用乘法分配律进行计算即可得到答案;
(7)将算式中的加数3.12改写成3.12×1,然后再利用乘法分配律进行计算即可得到答案;
(8)可用15除以0.15再除以0.4,最后结果不变;
(9)将算式中的加数1.5改写成1.5×1,然后再利用乘法分配律进行计算即可得到答案;
(10)可用73.8先减去13.8再减去1.64与5.36的和,最后结果不变;
(11)可用6.75减去3.75再减去0.9即可,最后结果不变;
(12)按照小数的四则混合运算进行计算即可得到答案;
(13)可用35.72减去4.9与(5.72+5.1)的和,最后结果不变;
(14)将算式中的减数0.25与减数0.75交换位置,算式中的0.75减0.75等于0,0.25减0.25等于0,0减去0结果还是0;
(15)交换5.3与0.1的位置,然后再利用小数的四则混合运算进行计算即可得到答案;
(16)可用12.7减去4.8与5.2的和,最后结果不变.
(2)将算式中的1.4改写成0.7乘以2的形式,然后再用6.3分别除以0.7与2,结果不变;
(3)将算式中的2.4改写成4乘以0.6的形式进行计算比较简便;
(4)将0.25改写成分数
1 |
4 |
1 |
4 |
(5)将算式中的加数1.5改写成1.5×1,然后再利用乘法分配律进行计算即可得到答案;
(6)直接利用乘法分配律进行计算即可得到答案;
(7)将算式中的加数3.12改写成3.12×1,然后再利用乘法分配律进行计算即可得到答案;
(8)可用15除以0.15再除以0.4,最后结果不变;
(9)将算式中的加数1.5改写成1.5×1,然后再利用乘法分配律进行计算即可得到答案;
(10)可用73.8先减去13.8再减去1.64与5.36的和,最后结果不变;
(11)可用6.75减去3.75再减去0.9即可,最后结果不变;
(12)按照小数的四则混合运算进行计算即可得到答案;
(13)可用35.72减去4.9与(5.72+5.1)的和,最后结果不变;
(14)将算式中的减数0.25与减数0.75交换位置,算式中的0.75减0.75等于0,0.25减0.25等于0,0减去0结果还是0;
(15)交换5.3与0.1的位置,然后再利用小数的四则混合运算进行计算即可得到答案;
(16)可用12.7减去4.8与5.2的和,最后结果不变.
解答:解:(1)2.5×3.2×12.5
=2.5×0.4×8×12.5,
=1×8×12.5,
=8×12.5,
=100;
(2)6.3÷1.4
=6.3÷(0.7×2),
=6.3÷0.7÷2,
=9÷2,
=4.5;
(3)2.5×2.4
=2.5×4×0.6,
=10×0.6,
=6;
(4)15.32×4+4.68÷0.25
=15.32×4+4.68÷
,
=15.32×4+4.68×4,
=(15.32+4.68)×4,
=20×4,
=80;
(5)2.55×1.5+1.5+6.45×1.5
=2.55×1.5+1.5×1+6.45×1.5
=(2.55+1+6.45)×1.5,
=9×1.5,
=13.5;
(6)2.95×101-2.95
=2.95×(101-1),
=2.95×100,
=295;
(7)3.12+3.12×99
=3.12×1+3.12×99,
=3.12×(99+1),
=3.12×100,
=312;
(8)15÷(0.15×0.4)
=15÷0.15÷0.4,
=100÷0.4,
=250;
(9)2.55×1.5+1.5+6.45×1.5
=2.55×1.5+1.5×1+6.45×1.5
=(2.55+1+6.45)×1.5,
=10×1.5,
=15;
(10)73.8-1.64-13.8-5.36
=73.8-13.8-(1.64+5.36),
=60-7,
=53;
(11)6.75-(0.9+3.75)
=6.75-3.75-0.9,
=3-0.9,
=2.1;
(12)27.38-5.34+2.62-4.66
=22.04+2.62-4.66,
=24.66-4.66,
=20;
(13)35.72-4.9-(5.72+5.1)
=35.72-(4.9+5.72+5.1),
=35.72-15.72,
=20;
(14)0.73-0.25-0.73+0.25
=0.75-0.75-0.25+0.25,
=0-0.25+0.25,
=0-0,
=0;
(15)5.3+0.1+5.3-0.1
=5.3+5.3+0.1-0.1,
=10.6+0.1-0.1,
=10.7-0.1,
=10.6;
(16)12.7-4.8-5.2.
=12.7-(4.8+5.2);
=12.7-10,
=2.7.
=2.5×0.4×8×12.5,
=1×8×12.5,
=8×12.5,
=100;
(2)6.3÷1.4
=6.3÷(0.7×2),
=6.3÷0.7÷2,
=9÷2,
=4.5;
(3)2.5×2.4
=2.5×4×0.6,
=10×0.6,
=6;
(4)15.32×4+4.68÷0.25
=15.32×4+4.68÷
1 |
4 |
=15.32×4+4.68×4,
=(15.32+4.68)×4,
=20×4,
=80;
(5)2.55×1.5+1.5+6.45×1.5
=2.55×1.5+1.5×1+6.45×1.5
=(2.55+1+6.45)×1.5,
=9×1.5,
=13.5;
(6)2.95×101-2.95
=2.95×(101-1),
=2.95×100,
=295;
(7)3.12+3.12×99
=3.12×1+3.12×99,
=3.12×(99+1),
=3.12×100,
=312;
(8)15÷(0.15×0.4)
=15÷0.15÷0.4,
=100÷0.4,
=250;
(9)2.55×1.5+1.5+6.45×1.5
=2.55×1.5+1.5×1+6.45×1.5
=(2.55+1+6.45)×1.5,
=10×1.5,
=15;
(10)73.8-1.64-13.8-5.36
=73.8-13.8-(1.64+5.36),
=60-7,
=53;
(11)6.75-(0.9+3.75)
=6.75-3.75-0.9,
=3-0.9,
=2.1;
(12)27.38-5.34+2.62-4.66
=22.04+2.62-4.66,
=24.66-4.66,
=20;
(13)35.72-4.9-(5.72+5.1)
=35.72-(4.9+5.72+5.1),
=35.72-15.72,
=20;
(14)0.73-0.25-0.73+0.25
=0.75-0.75-0.25+0.25,
=0-0.25+0.25,
=0-0,
=0;
(15)5.3+0.1+5.3-0.1
=5.3+5.3+0.1-0.1,
=10.6+0.1-0.1,
=10.7-0.1,
=10.6;
(16)12.7-4.8-5.2.
=12.7-(4.8+5.2);
=12.7-10,
=2.7.
点评:此题主要考查的是小数的四则混合运算和小数的运算中的简便运算.
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