题目内容
脱式计算.(能简算的要简算)
1840-725÷25×16
--
16.4+3.5+83.6+166.5
(+)×-
59+59×13+14×41
36÷[(-)×3].
解:(1)1840-725÷25×16,
=1840-29×16,
=1840-(30-1)×16,
=1840-30×16+16,
=1360+16,
=1376;
(2),
=(),
=1,
=,
=;
(3)16.4+3.5+83.6+166.5,
=(16.4+83.6)+(3.5+166.5),
=100+170,
=270;
(4)(+)×-,
=+-,
=1-,
=-+1,
=1,
=;
(5)59+59×13+14×41,
=(1+13)×59+14×41,
=14×59+14×41,
=(59+41)×14,
=100×14,
=1400;
(6)36÷[(-)×3],
=36÷[3-3],
=36,
=36×,
=24.
分析:(1)1840-725÷25×16,再计算1840-29×16时,把29看作30-1,计算起来较简便;
(2),运用减法的性质简算,同时注意运算符号的变化;
(3)16.4+3.5+83.6+166.5,运用加法交换律和结合律简算;
(4)(+)×-,在计算(+)×时,运用乘法分配律简算;
(5)59+59×13+14×41,此题运用乘法分配律的逆运算简算;
(6)36÷[(-)×3],先算(-)×3,运用乘法分配律简算,然后算括号外的.
点评:此题考查学生对四则混合运算顺序的掌握情况,以及对运算定律的灵活运用能力.
=1840-29×16,
=1840-(30-1)×16,
=1840-30×16+16,
=1360+16,
=1376;
(2),
=(),
=1,
=,
=;
(3)16.4+3.5+83.6+166.5,
=(16.4+83.6)+(3.5+166.5),
=100+170,
=270;
(4)(+)×-,
=+-,
=1-,
=-+1,
=1,
=;
(5)59+59×13+14×41,
=(1+13)×59+14×41,
=14×59+14×41,
=(59+41)×14,
=100×14,
=1400;
(6)36÷[(-)×3],
=36÷[3-3],
=36,
=36×,
=24.
分析:(1)1840-725÷25×16,再计算1840-29×16时,把29看作30-1,计算起来较简便;
(2),运用减法的性质简算,同时注意运算符号的变化;
(3)16.4+3.5+83.6+166.5,运用加法交换律和结合律简算;
(4)(+)×-,在计算(+)×时,运用乘法分配律简算;
(5)59+59×13+14×41,此题运用乘法分配律的逆运算简算;
(6)36÷[(-)×3],先算(-)×3,运用乘法分配律简算,然后算括号外的.
点评:此题考查学生对四则混合运算顺序的掌握情况,以及对运算定律的灵活运用能力.
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