题目内容
脱式计算,能简便的要用简便方法计算. 0.389×4×0.25 |
4.02×3.02+4.02×6.98 |
4.05÷0.81+2.4 | 65.4÷2.5÷4 |
86×9.9 | 1.76-[(0.74+0.26)÷0.8]. |
分析:(1)运用乘法结合律简算;
(2)运用乘法分配律简算;
(3)先算除法,再算加法;
(4)根据除法的性质简算;
(5)先把9.9分解成10-0.1,再运用乘法分配律简算;
(6)先算小括号里面的加法,再算中括号里面的除法,最后算括号外的减法.
(2)运用乘法分配律简算;
(3)先算除法,再算加法;
(4)根据除法的性质简算;
(5)先把9.9分解成10-0.1,再运用乘法分配律简算;
(6)先算小括号里面的加法,再算中括号里面的除法,最后算括号外的减法.
解答:解:(1)0.389×4×0.25,
=0.389×(4×0.25),
=0.389×1,
=0.389;
(2)4.02×3.02+4.02×6.98,
=4.02×(3.02+6.98),
=4.02×10,
=40.2;
(3)4.05÷0.81+2.4,
=5+2.4,
=7.4;
(4)65.4÷2.5÷4,
=65.4÷(2.5×4),
=65.4÷10,
=6.54;
(5)86×9.9,
=86×(10-0.1),
=86×10-86×0.1,
=860-8.6,
=851.4;
(6)1.76-[(0.74+0.26)÷0.8],
=1.76-[1÷0.8],
=1.76-1.25,
=0.51.
=0.389×(4×0.25),
=0.389×1,
=0.389;
(2)4.02×3.02+4.02×6.98,
=4.02×(3.02+6.98),
=4.02×10,
=40.2;
(3)4.05÷0.81+2.4,
=5+2.4,
=7.4;
(4)65.4÷2.5÷4,
=65.4÷(2.5×4),
=65.4÷10,
=6.54;
(5)86×9.9,
=86×(10-0.1),
=86×10-86×0.1,
=860-8.6,
=851.4;
(6)1.76-[(0.74+0.26)÷0.8],
=1.76-[1÷0.8],
=1.76-1.25,
=0.51.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
练习册系列答案
相关题目