来自罗智敏的问题
【下面各题,怎样简便就怎样算.19.98×37-199.8×1.9+1998×0.829999×7+1111×37[-(-)]×(70+)×.】
下面各题,怎样简便就怎样算.19.98×37-199.8×1.9+1998×0.829999×7+1111×37[-(-)]×(70+)×.
1回答
2020-05-06 23:56
【下面各题,怎样简便就怎样算.19.98×37-199.8×1.9+1998×0.829999×7+1111×37[-(-)]×(70+)×.】
下面各题,怎样简便就怎样算.19.98×37-199.8×1.9+1998×0.829999×7+1111×37[-(-)]×(70+)×.
(1)19.98×37-199.8×1.9+1998×0.82,
=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;