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(1)1.99×199.8-19.98×19.7简便计算(2)1999+999×999简便计算
人气:118 ℃ 时间:2019-11-04 04:24:16
解答
(1)1.99×199.8-19.98×19.7
=19.9×19.98- 19.7×19.98
=(19.9- 19.7)×19.98
=0.2×(20-0.02)
=0.2×20 - 0.2×0.02
=4- 0.004
=3.996
(2)1999+999×999
=1000+999+999×999
=1000+(1+999)×999
=1000+ 1000×999
=1000×(1+999)
=1000×1000
=1000000
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