1999×0.99×0.9=?(简算)
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1999×0.99×0.9=?(简算)
1999×0.99×0.9
=(2000-1)×(1-0.01)×(1-0.1)
=(2000-1-20+0.01)×(1-0.1)
=1979.01×(1-0.1)
=1979.01-197.901
=1781.109
=(2000-1)×(1-0.01)×(1-0.1)
=(2000-1-20+0.01)×(1-0.1)
=1979.01×(1-0.1)
=1979.01-197.901
=1781.109