| 19.98×37-199.8×1.9+1998×0.82 | 9999×7+1111×37 |
[ -( - )]×![]() | (70+ )× . |
=1998×0.37-1998×0.19+1998×0.82,
=1998×(0.37-0.19+0.82),
=1998×1,
=1998;
(2)9999×7+1111×37,
=1111×63+1111×37,
=1111×(63+37),
=1111×100,
=111100;
(3)[
-(
-
)]×
,=[

]×
,=
,=
;(4)(70+
)×
,=:(69+1+
)×
,=1+

,=1
(1
),=1
,=1
,=1
;分析:(1)19.98×37-199.8×1.9+1998×0.82,根据因数与积的变化规律将原式转化为:1998×0.37-1998×0.19+1998×0.82,然后运用乘法分配律进行简算;
(2)9999×7+1111×37,根据因数与积的变化规律将原式转化为:1111×63+1111×37,再运用乘法分配律进行简算;
(3)[
-(
-
)]×
,根据分数四则混合运算的顺序,按照分数四则运算的计算法则进行计算;(4)(70+
)×
,转化为:(69+1+
)×
,运用乘法分配律进行简算.点评:此题考查的目的是掌握小数、分数四则混合运算的顺序以及计算法则,并且能够灵活运用简便方法进行计算.