用简便方法计算. 98×105 58×69+31×58 125×43×8 69×40-44×40 4388-687-313 (48×25)×8.
(1)98×105,
=98×(100+5),
=98×100+98×5,
=9800+490,
=10290;
(2)58×69+31×58,
=58×(69+31),
=58×100,
=5800;
(3)125×43×8,
=(125×8)×43,
=1000×43,
=43000;
(4)69×40-44×40,
=40×(69-44),
=40×25,
=1000;
(5)4388-687-313,
=4388-(687+313),
=4388-1000,
=3388;
(6)(48×25)×8,
=48×(25×8),
=48×200,
=9600.
=98×(100+5),
=98×100+98×5,
=9800+490,
=10290;
(2)58×69+31×58,
=58×(69+31),
=58×100,
=5800;
(3)125×43×8,
=(125×8)×43,
=1000×43,
=43000;
(4)69×40-44×40,
=40×(69-44),
=40×25,
=1000;
(5)4388-687-313,
=4388-(687+313),
=4388-1000,
=3388;
(6)(48×25)×8,
=48×(25×8),
=48×200,
=9600.
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